Tips For Minimizing Data Usage
Download & update apps, games, music, etc. on Wi-Fi only
Some apps and music downloads can be very large, and the periodic updates can be as well. Don't enable automatic updates, and wait until you are home or on a trusted Wi-Fi network for large downloads.
Use streaming media on Wi-Fi only
Data-rich apps such as Pandora, Hulu, Netflix, YouTube, and other streaming services, as well as image-intensive sites, such as Flickr and Photobucket are best experienced on Wi-Fi.
Set email accounts for manual download
Sync email whenever you have a Wi-Fi connection, if possible. If this isn't feasible, set options on your email to download messages without images or attachments.
Turn off push notifications whenever possible and limit automatic background data updates
Check app settings to limit automatic background data updates if not needed.
Watch for applications that use location data in the background
Unless it's needed, turn it off.
Set your browser to block pop-up windows and turn off data loading
Set your browser to block pop-ups and disable automatic loading of images.
Use mobile-friendly sites when possible
Mobile-optimized sites strip out animated ads and large images, which can speed up the user experience and limit the data load.
Send pictures and short videos as MMS picture messages, rather than email attachments
MMS messages are instant and personal, compared to email, which often sits in an inbox. Utilize your messaging plan capabilities to help control your data usage.
Utilize an app to measure and manage data usage
There are a number of free apps available to measure data usage, including alerts as usage approaches plan limits and breakdown by application, which can give insights to help manage data usage.
For example, the "My Data Manager" app for Android (free version available on Amazon market and Google Play market) allows users to track Mobile data usage, Roaming data usage, and Wi-Fi usage. Users can enter the data plan limits for on-net and roaming, as well as billing cycle to ensure they stay under plan limits each month.