Both Europa and I have done articles about battery life and getting the most out of it here on EIC.
Off the top of my head, here's a quick list of things to think about
1) Brightness - keep it as low as you can, and use auto brightness option
2) Push - don't use it if you get a lot of email. Get a 3rd party app that uses notifications instead. Push talks too much and will impact battery life
3) Wifi- Use it when available, turn off auto notify of available networks.
4) Location Services. This one is more a preference thing, but I only allow location services to access apps that are specifically location based. No games, camera, or anything else.
5) This one is about general care. top off your battery when charging opportunities are available. Drain the phone every once in a while to reset the battery meter, and reboot the phone every 3-7 days. Make sure that you close webpages that auto-refresh and any apps that can actually run in the background like Pandora. This will make sure that you are not letting anything "slip by" using the charge when you didn't intend for it.
There are a lot of people on here that will argue some of my suggestions, but I average about 6-8 hours of usage a day, and when I connect to my charger at night, I'm usually between 30-40%. I use my phone a lot, and during the day, wifi is not available. I have everything on, and brightness is at about 1/3 of the slider.