Here are some tips for prelonging battery life:
1 - Don't use 100% screen brightness at all times - 50-60% is enough, only increase it when you need to then lower it again.
2 - If your planning to use the phone for long periods, 30 minutes or more constant use then once again use 25% or so brightness
3 - When browsing/surfing the net use the lowest possible brightness as this is the biggest battery killer. Unfortunately our AMOLED screens suck a lot of juice when displaying white...
4 - Try to keep most, if not all applications to manual updates only. Otherwise decrease the update frequency.
5 - Use an alternative launcher. I find for example using LauncherPro uses less resources/cpu/ram than the default touchwizz launcher. Therefore using less ram/cpu saves battery!
6 - If your gonna game for hours then I suggest 0% brightness!
7 - Last but least watch your apps. Some apps are poorly optimized/coded and can take up a lot of ram and cpu which then eats away at your battery!