There are a couple rules for good battery life with lithium-ion batteries... for 2 weeks run your battery completely dead then charge it completely to full without any little maintenance or half way charges... then after 2 weeks continue to do that at least twice a week... that will insure you battery stays in optimal condition.
As far as the phone goes... the power control widget is gold... add that to your home screen or close and keep active only what you need... If you have a task killer avoid killing everything... (Not to start that horrible debate) but if you are planning on using a task killer I have found that simply blocking apps that you don't use that run in the background can save about an hour or so of battery (That was however a test I ran on the Droid 1... I have not needed a task killer on the Droid 2) And last but not least if you have apps or widgets that update try to have them do it only as much as you need... (I find that my news widget getting updates every 10 mins might be a little excessive if I check the news every couple hours...
Using these guidelines for myself I am able to get about a 29-31 hour charge out of my Droid 2 with my usage being approx: 3 x 5-10 min voice calls, 5 texts per hour, 30-45 min of web browsing and gaming maybe twice, and the occasional time check... mileage may vary but this is pretty accurate for my day... most the time around that 30 hour mark my phone shuts itself off.
Hope this helps