ther have been many apps and disucssions on BL. heres some common tips.
screen to lowest brightness possible setting. background data always off unless using market. disable -use wireless networks- options, no gps, no location. also turn off *back up my data*. wifi always off not in use. screeen timeout no more than 2 minutes. turn off animations and transitions. setcpu with moderate settings (if you can do a screen off profile it will be beneficial but beware Sleep of Death.) no live wallpapers. minimum widgets or none. minimum homescreens or 1. startup manger. adfree. location cache app. and battery calibration to get the most juice.