A lot of smartphone and tablet data plans are not unlimited, and unlimited data could cost more than limited data in the US, and Canada. However, it is very simple to save data/bandwidth on your phone and tablet running Google Android.
I first recommend you use Opera Max which is a data compression app which compresses both mobile data, and wifi data to save bandwidth data on Google Android. It can compress videos, photos, and text on mobile apps like web browsers which don’t use an encrypted connection.
Google Chrome for Android also now has a Data Compression feature in its settings which you can turn on to saves you some data by compressing picture files.Google Android Data section in the settings to lets you see which apps use the most data, and help you manage your data/bandwidth better, so you use less data to help improve your internet speeds, pay lower data bills, and see improvements when it comes to phone performance, and your battery life.
The YouTube App, and other video streaming apps let you adjust the video quality to 144P, 240P, 360P, 480P, and higher resolutions. I recommend watching videos in 144P if you mainly listen to the audio, but not watch the video. 240P picture quality is better for watching video. 360-480P look nicer, but use more bandwidth. 720P, and higher resolution videos use the most bandwidth. It is best to not watch video if you are on an internet or data connection with low data limits since video uses a lot of bandwidth.
You can disable autosync on your accounts in Google Android Account settings in settings to stop Android from Auto-syncing to save more bandwidth by stopping auto sync. I think logging out of Facebook, Twitter, Gmail, and other apps also disable syncing while protecting your privacy. If you do not want to logoff your accounts, you can usually disable syncing in the settings for apps, or in the account settings in Google Android.
In Google Play App store settings, turning off auto-update will stop your apps from updating automatically which can save GBs of data. There is also a option to only update apps when connected to Wi-Fi.