Procedures such as occasionally turning off your iPhone for a minute or two helps along with calibrating your battery occasionally.
Check in location services as this will show by way of an icon what app is and has recently used your location which uses battery.
General, about, diagnostics and usage and choose, don't send.
Location services, system services and toggle everything off.
These are some of the most common known reasons of battery loss along with the usual wifi, bluetooth and screen brightness settings etc.
I prefer not to toggle everything off as i want to get the most from my iPhone 4.
I get around 1.5 days usage with moderate to heavy use. Im not a gamer.