That works too, but I was being serious.
If you dont need the GPS, turn it off. If you dont need the WiFi, turn it off. If you arent using Bluetooth, you guessed it, turn it off. I'd leave the data on, because it sort of defeats the purpose of the phone if you have a dataless data centric phone. But again, if you really want to extend the battery life, it'll help to turn it off.
Also be mindful you arent letting apps run as that'll aid in battery drain.