If you're having trouble getting your phone to last through the day on a charge, Android makes it easy to figure out where to get power savings. Head over to the battery section of the settings screen. You'll see a graph of the battery's discharge rate, and a list of running apps and services ordered by how much power they've been sipping (or guzzling). On many phones, the screen is the biggest culprit, so maybe you'll want to turn down the brightness to save some juice. Or perhaps there's one app that's chugging away in the background, chewing up battery, that you'll want to kill. Just click on that app, and click "Force stop" on the following screen.