The following are some suggestions to help reduce data usage on your Android while traveling. Please keep in mind, the wording or location of menus may differ for some devices
1. Disable Automatic App Updates on Cellular Data
Make sure your applications only update over Wi-Fi
Go to Apps > Play Store > Settings > Auto-update Apps > Set "Auto-update apps over Wi-Fi only"
2. Disable Background data
Prevent your applications from pulling data in the background when your not actively using them.
Go to Settings > Data usage > Background data > Turn it Off entirely or by selective Apps
3. Disable Auto Sync of Accounts
Go to Settings > Accounts > ...More > Disable auto sync
4. Disable Smart network switch
Smart network switch allows you to stay connected when you have a poor Wi-Fi connection. If your traveling and connected to local Wi-Fi (Hotel, Cafe, Restaurant), these Wi-Fi connections may not be reliable and your phone may automatically switch to using data from your KnowRoaming SIM if Smart network switch is on.
Go to Settings > Connections > Wi-Fi > Advanced > Disable Smart network switch
5. Monitor Application Usage
Browse through your installed applications and monitor which ones are using the most data.
Go to Settings > Data usage > Scroll through to see what applications are using the most data.