The Huffington Post has a useful slide show on saving iPhone battery life based on some common techniques used for all phones plus some special issues regarding what is an iOS 5.0 bug that Apple has acknowledged is affecting IOS 5 devices (not just the iPhone 4 or 4S). Apple said that a “small of number of customers have reported lower than expected battery life on iOS 5 devices,” but just because a small number have complained doesn’t necessarily mean it affecting a large number. Apple said it will release a software update in a few weeks.
To safe battery life the Huffington Post recommends (and you should go to the article for specific advice on how to do this on an iPhone)
1. Turn off feature that automatically sets time the zone based on your location
2. Get rid of push notifications you don’t care about
3. Turn down screen brightness (on all battery operated devices)
4. Lock your phone (helps it from turning on by mistake)
5. Turn off location services (like GPS) for apps that you don’t need or those that don’t really need to know where you are (applies to all mobile phones)
6. Turn off SIRI’s raise to speak function
7. Fetch (don’t push) your email (applies to Android as well)
8. Close apps that are running in background (also applies to Android)
9. Stop checking for WiFi all the time or just turn off WiFi if you don’t need it (all phones)
10. Go to the Genius bar at an Apple store (to see if they can help)
In addition to these, I recommend that you turn off BlueTooth if you don’t need it, GPS or any other function that isn’t necessary but drains battery life.