Most Android apps, if not properly checked can zap huge amount of data within the shortest time frame. Most free apps on android also make use of internet data to run adverts on their apps, even in background, most services run in background i.e checking for updates or just refreshing your contents. But with some measures put in place, it is now possible to minimize data consumption.
DISABLE INTERNET CONNECTION MANUALLY WHEN NOT IN USE
I believe most people already know this because it seems to be the easiest way to conserve data. In most devices, all that is needed is to slide down the notification bar then hit the data connection icon to turn it ON or OFF. This does not only minimizes data, it also conserves battery use.
DISABLE AUTO UPDATE APP OVER MOBILE DATA
How would you feel waking up to realize your game app of 1.5GB was automatically updated over night? That is why you would need to disable auto update of apps on play store over mobile data. To do this, open your app menu=>play store=>menu (i.e the 3 bars on the left top corner)=>settings=>auto update apps only on WiFi. By doing this, you have successfully conserved your internet data.
RESTRICT BACKGROUND DATA
A couple of apps make use of your data to run in background thereby consuming a large amount of data. While the foreground usage shows you the amount of data you used while on the app, the background usage shows you the amount of data used by the app in its idle state. Always uninstall irrelevant high data consuming apps. To restrict this, go to settings=>data usage=>hit the 3 dots on the right down corner to restrict background data.
RESTRICTING AUTO SYNC SETTINGS
Android apps would automatically synchronize in other to fetch stuffs if not disabled. The advantage of syncing is that it fetches you your information such as e-mails, IMs notifications on time by refreshing your contents often which in turn consume a large amount of data. Turning this off would mean you would have to manually refresh your mailbox to get new mails. To do this goto settings=>Account=> (select any of the account e.g mail)=>hit the 3 dots at the right down corner=>tick the box to cancel sync and minimize data use.