Close apps when you're finished with them.
When you switch from one app to another, some apps, such as the Browser app or the Music app, run in the background, which uses battery power.
To minimise battery usage, you have to close the apps as you finish with them.
Tip 2 :
If your phone has a camera flash, turn off the flash.
For more tips follow here: http://answers.techzim.co.zw/14392/tips-3-and-4-for-extending-battery-life-of-your-phone