1. Stop WhatsApp images appearing in your camera roll
If your friends send you loads of stupid pictures on WhatsApp, and you don't want them mixed in with all your amazing photos, it is possible to keep WhatsApp images separate so they don't appear in your camera roll.
Enter the folder you don't want shared (in this case, WhatsApp Images)
Tap the plus button at the bottom of the screen
Name the new folder .nomedia
That should stop any media in that folder from showing up in your camera roll.
2. Lock WhatsApp
If you're keen to keep your WhatsApp private, you can use any number of security apps to set a passcode for the app. AppLock is a popular choice.
3. Disable media auto-download
If you're running low on mobile data, it might be worth turning of the automatic download of media in WhatsApp, at least until you hit the monthly reset. To do this, head to Settings > Data usage. In this menu, ensure you untick the boxes in both When using mobile data and When roaming.
4. Switch your WhatsApp chat history between phones
However, if for any reason you need to move your WhatsApp history over to a new device without using Google Drive, it's still a pretty painless procedure. All you need is a microSD card and a few minutes to spare.
Insert the microSD card into the device that has WhatsApp on it
In WhatsApp, go to Settings > Chats > Chat backup
Remove the SD card and place it into your other device
Install WhatsApp on the other device
WhatsApp should detect the backup and prompt you to restore it, which you should do
If you need to move the backup, use a file explorer to find '/sdcard/WhatsApp' and move it to the correct folder.