Using a custom ROM will improve the battery life, but I know you're not quite ready for that one yet. SwiftKeyed from my Samsung Galaxy S2 with Tapatalk
Try reducing the screen brightness that should help a lol and make sure you don't have apps running in the background. Might need to get a task killer for that...
Xda forums, definitely required reading.Sent from my Samsung Galaxy Note
This tip sound counterintuitive but may help as well...I use it with an app called llama to auto disconnect my wifi when I leave home or office (uses cell tower ids) http://www.androidcentral.com/android-101-save-battery-keeping-wifi-alive?style_mobile=0
Using a custom ROM will improve the battery life, but I know you're not quite ready for that one yet.