To save battery life turn down your brightness. It's not the best way to save battery life but it helps.
Here's 1 of the best ways to save battery life. Turn on your airplane mode and turn on the wifi also. The wifi works Perfectly fine but you just need good signal strength.
Here's another major way to save battery. Go to settings>general>accessibility>re-duse motion. This stops your apps from moving making it look like your background moving.
IOS 7 let's your phone automatically update apps. To turn this off go to settings>iTunes and app store>and then go to automatic downloads and turn off updates.
When your not using your app anymore clear your apps by double clicking your home button and sliding the rectangular boxes up, which is called clearing it.
Unless your use Siri often then turn off Siri because Siri takes a lot of battery life without even using it. And you just don't know it.
Turn off your location services that drains battery to. Go to settings>privacy>location services.
Turn off wifi when your not using it, turn off Bluetooth if you don't use it, and turn off the do not disturb button. If you don't want any notifications them just turn off your notifications.