(note this tutorial is explained with android 4.2.2 settings running on a samsung galaxy grand smartphone)
1. Keep Background Data Restricted for certain apps
Most of the apps connect to internet by themselves even if they are not running in foreground, they eat your phone’s data as well as the battery life. By following this method you can not only save your internet data, also the battery life of your phone considerably. For this we have to restrict applications to use Background Data, so that they cannot connect to internet in background.
For certain apps which you don’t need to be running in background and consume data you can follow these steps to restrict them
Go to Settings-> Connections-> Data Usage
You can see your total data usage for a certain period (set by the user) here. Scroll down to see data usage by all apps and activites
Tap on any app to see the detail of data used. You can see the foreground and background data used by the app.
Scroll down. Select ‘Restrict background data’ option. A tick mark will be placed in the check box. You are done now. Similarly do for other apps.
There are two benefits here, firstly your internet data is saved and you have more control over your data usage. Secondly it saves your phone’s battery as the apps are unable to connect to internet in background.
(Note: Do this trick for only those apps which you don’t want to be using internet in background. If you restrict apps like whatsapp, facebook etc., you will no longer be getting notifications of these apps. Some apps which can be restricted are Google Play Store, Google Services, Google Search, Software Update, Youtube etc. You can manually check updates for these apps after few days)