If you’re looking for a free Twitter app that is accessible, check out Twidere for Android by Mariotaku:
https://play.google.com/store/apps/details?id=org.mariotaku.twidere&hl=en
This is a very brief guide to get started.

Immediately after Twidere installs from the Play Store, you’ve got two preliminaries to take care of. First, the app tells you to log into Twitter. Just tap OK or Continue to launch your browser, enter your Twitter user name and password, and tap the sign in button. Second, the app brings up a series of settings screens. Tap Next to move through them, making changes if you have convictions or leaving things as they are if you don’t. At the end of this process, you may be asked to allow location and one or two other things.

The Twidere main screen is pretty simple. Across the top are four tabs: Home, Interactions (i.e., Mentions), Trends, and Messages (i.e., Direct Messages). In the bottom right corner is a New Tweet icon. The first time you visit a tab, the screen displays no tweets or messages; you need to refresh to populate the screen.

To visit a tab, either tap the tab icon at the top of the screen, or swipe left or right with two fingers. For example, let’s say you’re on your timeline and you want to go to your mentions. Either tap Interactions, or swipe left once with two fingers.

To refresh the screen, long-press its tab icon. For example, if you want new tweets to appear, long-press Home.

To open the menu, touch the very left edge of the screen, then swipe right with two fingers. This is one of those things that takes a little practice, then works right every time.

Once tweets are displayed on the screen, each has three lines of information. The top line is the sender’s name and Twitter handle. The middle line is the sender’s profile icon and the tweet itself. The bottom line is a row of controls, which varies a little. Typically, controls are Reply, Retweet, Like, and an unlabeled button I’ve called More. Tapping More brings up additional controls, like Share, Copy, and Add to Filter. Exploring is the best way to read the screen.

To send a new tweet, tap the Compose icon in the bottom right corner. The new screen displays an edit box (above) and the keyboard (below). To the right of the edit box are a check box for adding your location and the Send button. Below the edit box is a row of icons for changing the account, adding an image, taking a photo, and saving as draft.

The app is very accessible. The only hiccups I’ve found are the unlabeled button in the third row of each tweet and the fact that TalkBack doesn’t announce, “Selected,” when you touch the tab for the screen you’re on.

Volkron Checkbook is a ledger for keeping track of your bank accounts. Its Play Store link is
https://play.google.com/store/apps/details?id=com.volkron.checkbook.andr...

The app is free and completely accessible. I haven't found any unlabeled buttons or other wonkiness. Well, there is one thing, but it's pretty minor. I'll mention it below.

The app's tag line is that it's simple and elegant, and this is true. In fact, the app is so simple and elegant that it's confusing when you're new to it.

When you open the app for the first time, you find Open Navigation Drawer in the top left corner, More Options in the top right corner, Default Account near the top of the screen, and New in the bottom right corner. Tapping Open Navigation Drawer lists your accounts at the top and some preferences farther down. Tapping More Options lists various search/display filters. Tapping New brings up a new transaction form.

To create an account, tap Open Navigation Drawer, then Settings, then Accounts. This brings up a screen with your existing accounts (i.e., Default Account) near the top. There's also an Add button in the top right corner. For your first account, tap Default Account, edit the name, and fill out the rest of the form. For additional accounts, tap Add and fill out the form. If you want to delete an account, tap the name of the account, then tap Delete in the top right corner. The new account screen is pretty basic, really just the account name (e.g., Checking, Savings) and the starting balance. When you're done, tap Save in the top right corner.

The next time you open the app, you find yourself on the last screen you worked on. Most likely, this is the account you moved money into or out of most recently. the name of the account is at the top, and your transactions appear as a list, with the oldest at the bottom.

To create a new transaction, tap New in the bottom right corner and fill out the transaction form. Information appears as a list: amount at the top, name of the party giving you the money or taking it from you (e.g., AT&T), Category (e.g., phone bill), number or code (e.g., check number or invoice number), date, and Notes. To the left of the amount is a minus sign, which TalkBack announces as "Switch." Tapping this symbol changes it to a plus sign, which TalkBack correctly announces. the edit boxes for Name and Category each have a button to the left for bringing up a list of names and categories you use often so you can just tap the one you want. Btw, when you install the app, it doesn't have any suggested names or categories, but each time you type a new one, it is saved for you automatically. When you finish filling out the transaction form, tap Save in the top right corner.

To work with a different account, tap Open Navigation Drawer to move to the screen with all your accounts and with a few preferences. Then tap the account you want.

This is enough to get started. The rest is easy enough to figure out.

Volkron Checkbook has a modern interface and is 99% accessible. I also like the way it displays and filters transactions on the Account and Statement screens. Unlike a similar app by Digital Life Style Solutions, Volkron doesn't have options for recurring transactions, like payday and auto bill pay, and it doesn't really let you export your files. You can back your information up as a DB file, but if you don't have a database app, you can't really do anything with that. The Play Store description for Volkron says these two features are forthcoming as premium features. When they come, the app will definitely be worth paying for.

Introduction to Android.

Android is the operating system of your phone. Much like Windows is to a computer; it helps you control all functions of your phone.
Firstly, if there is something you don't like about the way your device works from the file explorer, to the phone dialer, to the voice recognition engine to the browser or any other aspect of your device's interface or operation, likely you can change it.

Initial startup with Voice Assistant:
When you first power on the device, to activate voice assistant (the built in screen reader); simply hold 2 fingers on the surface of the touchscreen. After about 5 seconds it will announce tell you to keep holding down on the screen if you wish to enable it. A few seconds later you will hear the screen reader start up. You will at this point be presented with the startup wizard that will take you through connecting your phone to a wifi hotspot, connecting your google / gmail account and setting up the initial parameters of the device. Depending on what version of Android your device uses, you may need a set of earphones in order to hear your password spoken out.

Talk Back, the screen reader:
Samsung and Google have their own adaptive technology layers. Some of the tools need to be installed on a Samsung device in order to make it usable.
For example, Samsung has its own screen reader called "voice assistant", it is not very good. (e.g. doesn't support web content, keyboard access or braille very well or at all). You need to install Talkback (Google's screen reader) separately from the play store.
You can do this either yourself or ask for sighted help to do this so if you are asking for sighted assistance, you can start by turning off Voice Assistance before passing the phone ober.
1. From the Home button, slide your finger up slightly and you should hear Apps. Double tap to open it.
2. Use two fingers slightly separated and swipe upwards with short strokes till you get to the bottom of the list.
3. Slide your finger till you hear Settings and double tap to open it.
4. Use two fingers slightly separated and swipe upwards with short strokes till you get to the bottom of the list
5. Slide your finger till you hear Accessibility and double tap to open it.
6. Slide your finger till you hear Vision and double tap to open it.
7. Slide your finger till you hear Voice Assistance and double tap to open it.
8. Slide your finger on the upper right of the screen till you hear Switch ON and double tap to set it to Off.
9. An alert pop up will warn you that typing OK will turn off the Voice Assistance.
10. Double tap on OK and Voice Assistance will be turned off.

To install Talkback from the Play Store, your sighted friend will need to do the following:
1. From the Home screen, tap on Apps.
2. Scroll down a bit and tap on Play Store.
3. Tap on the Search button on the upper part of the screen.
4. Tap on the edit field and type Talkback.
5. Tap on Google Talkback.
6. Tap on Install.

Once installed, you will not be able to have the two running at the same time. Enabling Talkback will automatically disable Voice Assistance. To perform the switch, you will need to do the following:
1 From the home screen, tap Apps.
2 Tap Settings.
3 you will need to scroll down a little to Tap on Accessibility
4 Tap Vision.
5 Scroll down past the Services heading and Tap on TalkBack.
6 Tap the slider to enable Talkback.
7. An alert screen will pop up requesting permissions.
8. Tap on OK and the switch is done.

Talk Back Tutorial:
To familiarize yourself with the gestures, you should practice the tutorial by going to settings then slide and double tap on accessibility then slide and double tap on talkback then slide and double tap on settings then slide and double tap on Launch Explore by Touch Tutorial

Below is a list of the most common gestures used with an Android phone.

Gestures:
You use a single finger swipe left to go forward and swipe right to go back through the items on a screen.
You hold your finger on the screen to open a menu related to the shortcut on the screen.
You double tap anywhere on the screen to activate the item that has the focus.
You use 2 fingers (swiping left, right, up or down to scroll in a list, scroll on a page or scroll around a multi-screen layout.
You can pair a gesture with a limited choice of commands. By default, the following gestures work:

Global menu
Draw an upper case L on the screen

(i.e. touch the surface of the screen and quickly draw a line down, than continue to the right and raise your finger) to open the global menu to access reading commands like read all, read from last touched item, spell last utterance, the quicknav commands and also there are a few buttons for global commands like disable talkback temporarily and talkback settings.
Previous screen
Draw an upper case L backwards
(I.e. touch the surface of the screen and quickly draw a line down, than continue to the left and raise your finger) to go to the previous screen
Local menu
Draw an upside down upper case L
(i.e. touch the surface of the screen and quickly draw a line up, than continue to the right and raise your finger) to go to the local menu where you will find specific commands for the field or control that currently has focus such as the label button command if focus is on an unlabeled button or the paste command if the focus is on an edit or input field.
Home
Draw a backwards and upside down upper case L
(I.e. touch the surface of the screen and quickly draw a line up, than continue to the left and raise your finger) to go to the “home” screen

It does take a little practice to learn how to do the "L" based gestures at first and it is important to listen to the audio cues that talkback provides to advise you if talkback recognizes the gesture you just completed as a valid "L" gesture.

Configurable gestures:
To configure the unused gestures, go to settings then slide and double tap on accessibility then slide and double tap on talkback then slide and double tap on settings then slide and double tap on Gestures.
Read the list of gestures and find an unassigned gesture.
Double Tap on it to open the list of commands that are available to associate with the gesture.
Select the desired command by double Tapping on it and the dialog box will close and you will be back at the gestures screen.
You can try the new gesture immediately.

Suggested gesture configurations for quick navigation and reading:
Swipe Up “Read from next item”
Swipe down “ Next navigation setting”
Swipe Left “Previous item”
Swipe right “Next item”

In the Talkback settings screen, you can customize your talkback gestures and even experiment with some new ones such as "shake to activate" which many people set to "read all"; so that when they shake their device it reads out the entire screen to them.

Nova Launcher:
When your device completes the initial startup wizard, you will be in your device's "launcher". Depending on the manufacturer and device this launcher could be the google now launcher, senseUI or any of a host of other launchers. Many people will install Nova Launcher to replace the default launcher of the device.
Once installed, you must enable it by double tapping settings then slide and double tap on accessibility then slide and double tap on services then slide and double tap on Nova Launcher.

The desktop, the first screen you will encounter when unlocking or starting up your phone or when you press the Home button, will likely have several pages to the left and several pages to the right; each page contains a grid view of icons. At the bottom, you will encounter a line called the dock which usually contains the following icons, Phone, Apps and three others that you may choose amongst the ones that you use most often.
The Phone icon is the icon used to control all calling functions of the cell phone.
The app drawer contains a grid view of all the apps you have installed on the device.

Below that line, at the very bottom, on each side of your Home button, is another line with the following icons that appear as needed. Back, Home and Recent Apps
Back icon, returns you to the previous screen
Home button, returns you to the Desktop screen.
Recent Apps icon opens a screen with the apps presently in use or in memory. You would use this screen to close apps that are not being used to free up memory.

Making your phone easier to use.
Extending Screen time out
You may want more time of inactivity before the screen locks. This is controlled with the screen time out option. To adjust it, go to Settings then slide and double tap onDisplay then slide and double tap on Screen Time Out. 5 options will be offered, 15 seconds, 30 seconds, 1 minute, 5 minutes or 10 minutes. We suggest double tapping on 5 minutes.Your choice will be saved and you will be returned to the previous screen.

ChangingAlternative the keyboard layout,
Another keyboard you might consider installing is the blind accessibility keyboard.
You can find it in the Play store by typing the following link:
https://play.google.com/store/apps/details?id=de.bright_side.blind_acces...

It supports both double tap and touch typing.
Key size can be adjusted for more precise accuracy.
Layout can also be adjusted.
Once installed, you must enable it by going to Settings, then slide and double tap on General management, then slide and double tap on Language and Input, then slide and double tap on Default keyboard, then slide and double tap on Blind Accessibility US English.

Lock the screen to Portrait Orientation:
In order to have better control and stability while using your phone, it is best to keep the screen orientation locked in portrait. Nova Launcher forces this orientation throughout all applications. To access Nova Launchers settings, you need to be at your phones desktop.
Once at the desktop, press the Home button. This will open the Nova Launchers Settings panel. Double tap on the Settings button, then double tap on the Look & Feel item. Slide your finger till you find Screen Orientation and double tap to open it. Slide your finger to the Force Portrait list item and double tap it. This will save your choice and bring you back to the previous screen.

Using the phone:
Press the HOME button or slide your finger from left to right in the middle of the screen to answer the phone when it is ringing.
To hang up the phone, press once on the power button.
To call someone in your contacts list, double Tap on the phone icon, first icon at the bottom left of your screen. Then double Tap on the Contacts tab, the tab directly below your search edit field and double Tap on the person’s name. If you have more than one number for that contact, you will be presented with the list of numbers available. Double Tap on the desired number to start the dialing process.
Voice Search
You can use the voice search button located at the right of the Search edit field. Double tap on it, you will hear a blink sound, say the name of the person you want to call or the numbers you want to dial. A different blink sound will be heard once the phone has stopped listening to your voice and the phone will dial the persons name if it recognizes it in your contact list. If that person has more than one number, a list of numbers associated will be presented. Double tap on the number you wish to use. If you have only said the numbers to be dialed, it will dial them for you.

Using a regular Keyboard with your phone:

You can use a regular computer keyboard with an android phone by plugging it to the mini USB plug using an OTG adapter but only the following keys can be used.
The "Menu" key is usually the key to the right of the right Windows key. (sighted users describe it's legend/label/icon as a menu) Commonly called the Application key.
At the home screen:
Menu + W = change wallpaper
Menu + M = manage applications
Menu + N = show notifications
Menu + A = add item to homescreen
Menu + S = new search (or you can just start typing)
Menu + P = open settings
Home + B (or Search + B) = open browser
Home + C (or Search + C) = open contacts
Home + L = open calendar
Home + Esc = exit back to homescreen
In the browser:
Menu + N (or Ctrl + T) = new tab
Menu + I (or Ctrl + I) = zoom-in on page
Menu + O (or Ctrl + O) = zoom-out on page
Menu + J = open download manager
Menu + L = open search bar
Menu + R (or Ctrl + R) = refresh current page
Menu + F = find on page
Menu + B = open bookmarks
Menu + H = view browsing history
Menu + D = add bookmarks
Menu + S (or Ctrl + S) = open social network sharing
Menu + G = page info
Menu + E = select text
Menu + P = open browser settings
Menu + W (or Ctrl + W) = closes the current open tab
FN + Tab = toggle browser toolbar on/off when it's hidden
Ctrl + Shift = select input method (universal outside of browser also)
In Gmail:
C = compose new message
L = go to Label menu
X = check message in Inbox
V = add Label to current message
M = delete highlighted or checked messages
Alt + Up = go to top of Inbox
Alt + Down = go to bottom of Inbox.
General:
Shift + Backspace = Forward delete (like a full keyboard "Delete" key)
Ctrl + X = Cut
Ctrl + C = Copy
Ctrl + V = Paste
ALT + TAB = Show recent apps window. Keep your finger on the Alt key and press on the right arrow key to cycle forward between apps or press the left arrow key to cycle backward. Once on the desired app, your finger must still be on tha Alt key, press the enter key to activate it.

Recommended Apps to install:

Google Talkback –
https://play.google.com/store/apps/details?id=com.google.android.marvin....

Google Keyboard –
https://play.google.com/store/apps/details?id=com.google.android.inputme...
Nova Launcher –
https://play.google.com/store/apps/details?id=com.teslacoilsw.launcher&h...

Google Keep –
https://play.google.com/store/apps/details?id=com.google.android.keep&hl=en

@voice aloud reader –
https://play.google.com/store/apps/details?id=com.hyperionics.avar&hl=en

File Commander –
https://play.google.com/store/apps/details?id=com.mobisystems.fileman&hl=en

Aqua Mail –
https://play.google.com/store/apps/details?id=org.kman.AquaMail&hl=en

Additional Refferences :

Instructions for using the Google keyboard

- https://support.google.com/accessibility/android/answer/6110948?hl=en

Inclusive Android:

http://inclusiveandroid.com

National Braille Press's Getting Started With Android:

http://www.nbp.org/ic/nbp/ANDROID.html