How to make my battery last longer?

I have an iphone 4s how can i make my battery charge last longer?

Don't use it.

Every-so-often it's a good idea to let your battery drain completely and then recharge completely with the power off.

Well, here is what I did using my iPod.

Brightness:
Turn it down a notch. This drains it a lot.

Double tap the home button after unlock:
Hold one of the apps down there until the x marks come up. Clear out the whole bottom of all apps you can remove. This will also help long-term.

Generally, be more cautious on how much you use it, don't leave it open when you aren't doing anything, and don't constantly switch screens.