How to Increase Battery Usage Life of an Android Devices

1) For Better Process/Task Management Use Some Free Apps From Android Market Like Advance Task Killer Pro.

2) Kill The Task Usage Frequently With Advance Task Kill.

3) Try To Install Less Apps On Your Phone Coz Few Running Application Use Battery Internally.

4) Clear Ram Frequently.  

5) Disable Background Application Usage ...(Go To Menu-Settings-Accounts And Sync-Turn Off Background Data)

6) Do Not Use Live Wallpaper (If U Want Extra Battery Life Else You Can Use Not A Problem ;) )

7) Try Use Pattern Lock You Will Understand Automatically Why I Am Saying Like This.

Ok These Are The Few Things That I Marked That Really Helps Me Building My Battery Life To More Than 4 Day Of  Use ...