Battery life on iOS Devices is pretty good anyway. But when you find yourself in a tough spot where you need to conserve your battery, these tips might prove handy -
1. Decrease your brightness
Perhaps seems a little too obvious, but most people ( and I confess, this includes me ), will keep their iPads / iPhones on full brightness merely for the better screen looks.
2. Close all running apps
This might be a little confusing. When you press the home button and your Device takes you back to the home screen the previous app has not closed. It is still running in the background carrying out all the tasks it might have been if it were in the foreground. Unless you want your app to continue runnning in the background, simply close them by double tapping the home screen to reveal a slide in bar of all running apps. Quit them by touching and holding on any one and then touch the little red 'minus' button on any app. To close the bar simply tap anywhere else on the screen or press the home button again.
3. Change Mail Push Time
Accquiring data from your mail server every 15 minutes can take up a lot of battery life. Increase this time interval or set it to manual by going to Settings --> Mail, Contacts and Calendars.
4. Switch off Wi-fi, Blutooth, Location Services and Push Notifications
Disconnect from bluetooth devices like keyboard and switch it off in settings along with Wi-fi, Location Services and Push Notifications
5. Avoid Videos, Games and other graphically intense applications
Avoid playing games, watching videos or using other applications which may consume a lot of battery