Here is what I do.
1. Unless in use, turn off GPS, Bluetooth, Wi-Fi
2. Go into settings>location & security>uncheck "use wireless networks" & "Use GPS satellites" & "Enable Assisted GPS"
3. Go into settings>battery manager>battery settings>select "Maximum Battery Saver"
4. Go into settings>data manager>email & corporate sync>email delivery>turn off data push & set fetch schedule for 1 hour
5. Don't use social networking widget
You can also go into settings>sounds>uncheck "haptic feedback"
FYI...I do not think task killers are a necessity, but they do make it easy to kill a program (if needed)