Need more information. What are you using it for? How long does it last? How old is it? What update are you on? What carrier? With just a general statement such as this, I'll give you some general items.
(If you're on Verizon) Make sure that you’re on the latest version, because it actually improved battery life. Settings/About Phone/Software information/Software version: VS98512B
If you are in an area where you have crappy signal strength, you’re going to drain your battery faster.
If your location is on, but you do not have a clear view of the sky, you’re going to drain the battery faster.
If you’ve had the phone for a while and the battery life has gotten worse, do this:
Let the phone die to 15% or less (but try to never let it go below 7%).
Turn the phone off
Plug in the OEM battery charger and let it charge fully. (I recommend over night.)