As with any android device, managing your power usage can help extend your battery life. Quick tips:
1) Turn off Roaming. Saves on singal searching.
2) Turn of 4G unless you need data now. (I wish I had an easy 4G switch) LTE sucks power.
3) Turn down the brightness. Autobrightness is ok, as low as you can is better (I keep mine on the lowest auto setting and only change it if I'm outside mid-day, as that's the only time it's an issue for me)
4) Use Wifi when you can for data, turn wifi off when you aren't using it.
5) Turn GPS off when you don't need it.
6) Don't synch things often. Facebook, twitter, email, and other apps will all try to synch in the background. Turning it down/off will help save battery.
7) (Special for the Nexus/S3) turn off NFC (Near Field Communications). Turn it on when you need it (Google Wallet, android connect).
8) Turn off Bluetooth unless you're using it (see a pattern)?
I was sucking battery like mad for a while when I first got it. After I finally tweaked everything, that helped a lot. I also found some apps suck more battery life than others, such as swapping out The Weather Channel app for Weather Bug Elite (which didn't work till about 2 weeks ago on JB) actually saved me 10% of my daily battery usage (Probably has something to do with how they deal with background data and location).
Finally, I suggest running your battery down to near device death a few times. It seems to help calibrate the battery a bit. Do NOT to the run down, pull battery, restart till it won't thing, as that can kill the battery. Just run it down to under 5% and then charge it fully a few times.
Depending on your usage, your battery life will improve. Now that I don't fiddle with my new toy as much, I can get a full day (~16 hours) with 40-50% left with a few phone calls (maybe 10-30 minutes worth), ~4 hours of local music playing, and maybe 1-3 hours of other app/phone use (games, data usage, etc).
Also, if you can, try to use darker schemes. White/bright tends to eat more battery screen time than dark/black. I'd swear I got some extra battery life swapping from the default pulse live wallpaper to the darker bubbles wallpaper.
Also, I have the extended battery from Sprint, though I didn't notice a huge difference. I'd recommend looking into it, as the extended battery back on that is pretty tame compared to some of the other ones online.
Also, you can try clearing your caches (regular and Delvik) and let it "reoptimize" your apps. Not sure if that helps, but it can't hurt.
(yeah, lots of alsos. Sorry)