Personal experience
-Take off widgets, they use data, RAM, and power
-Kill any active antivirus such as lookout and get a passive(low impact) one like bitdefender
-Dim screen to 50%
-Try to use Wifi where available.
-Change sync settings to sync once every few hours
-open running aplications and kill services not used
-Unistall task killers
-Root and Rom, Rom such as liberty routinely leaves me with 575 bits of -RAM (less programs running) r3blurred incorporates the .893 fixes exception of Kernel and Radio.
-TURN OFF LATITUDE... HUGE KILLER... its syncs all the time. GPS Kills Battery
I personally keep my GPS on and my 4G on all the time. GPS IS a draining ONLY if its actively in use. I keep mine on* for my anti theft and for maps when I use it.