Welcome to Android Central! There are so many factors that contribute to battery usage that you really need to give us more information before we can give you good answers. We need to know how heavily you use your device, what you use it for (e.g., gaming, videos, music, emailing, etc.), and how old the device is (to get an idea of how old the battery is). It would also help to see screenshots of your
Settings>Battery screen.
Task killers don't really help, and in fact they can hurt battery life. Apps you kill will often restart on their own, because that's how Android works. Killing the app takes battery, and automatically restarting on their own takes battery. Don't use task killers unless a particular app seems to be malfunctioning and working too much.
See this guide for more info and tips:
http://forums.androidcentral.com/am...how-tos/298919-guide-battery-saving-tips.html