Do the following to save battery:
1. Freeze unwanted apps using Link2sd/app quarantine.(Needs root)
2. Do not download a lot using the Edge or 3G connection. It’s better to use Wi-Fi.
3. Uninstall apps you don’t need.
4. Use a firewall like Droidwall, to prevent unwanted apps from accessing the internet.(Needs Root)
5. Use Adfree to remove ads from your device (Needs root)
6. A reduced brightness helps a lot.
7. Switch off Bluetooth when not in use.
Don’t forget to use your android phone/tablet to the fullest.