Out of the Box
When you take the device out of the box, there are a few things you should disable or adjust to improve its battery life.
- Turn off GPS
Although GPS should only be running when you want it to (like when running Google Maps, Facebook or Foursquare), it's usually wise to keep it off until you really need it. Half the time the phone's coarse location is good enough for everything except Driving Navigation, and GPS doesn't work indoors unless you're near a window anyways. More recent versions of Android have a settings ribbon as part of the navigation dropdown now, and it makes switching common settings like WiFi, GPS and Sound fairly simple.
- Turn off 4G
Some of the more modern phones usually have a 4G option. For the most part you won't really need this unless you're either downloading a huge application or watching high definition video.
- Turn off Automatic brightness
Located in Settings > Display > Brightness, the brightness detection can be useful occasionally, but usually it's only noticable in low-light environments.
- Choose Static Wallpapers instead of a Live Wallpapers
The live wallpapers look really cool and can definitely sell phones, but in the end aren't incredibly useful. Generally speaking I haven't seen a live wallpaper that has been worth sacrificing battery life for. If you like the Nexus, Galaxy or Live Aquarium wallpapers, just know that what you gain in animation, you lose in power.
Even with all these changes you'll still have to keep an eye out for power-intense activities. The good news is that Task Manager apps are now usually included to help users see where their power's going.
- In Settings > Applications you have a bunch of options available to better manage your applications.
- Battery Usage lets you see if any applications are running in the background more than you're expecting. If something's running more than you want, check the application's settings to see if you can disable or reduce the background checks. If you don't have the option, email the developer and see if they could add the feature. If they have a mobile web application, switching to that instead of a native application may be a good alternative as well.
- Memory Usage helps if you're running out of space on your phone. Usually games and multimedia editing tools use a lot of resources here, although some social networking and content publication applications have internal storage that can take up space too. In some cases you can adjust the application's cache, although if your phone needs to hit the Internet too much it'll drain the battery more.
- Third Party Applications
If you're looking for other ways to tweak performance, there are some applications out there that can give you additional help. Personally I don't use any, but I thought I'd add them to be more complete. Let me know if there are additional resources and I'll add them as I can, with descriptions if I have used it.