Originally Posted by dyehya
One MAJOR thing to save power is DO NOT MESS WITH CPU SETTINGS!
Do not use 3rd party apps like Voltage Control or SetCPU or even the built in Performance settings as modifying the settings will increase the minimum clock to 200MHz which will greatly reduce battery life than NOT messing with them. This is a known issue and will be addressed in a future release!
If you DO decide to run a custom kernel, (NOT, I repeat NOT recommended or supported by CM9 devs) I'd suggest Control Freak. I ended up with a 200mhz min, and with that app managed to get deep sleep and 100mhz back. WITH uv and some minor oc. My battery life is great.
Head on over to the app thread here: http://forum.xda-developers.com/show....php?t=1072403
Another thing that can save battery, Screen Filter from the Market (Play Store now I guess) can dim our screens lower than the lowest stock increment. Useful for dark environments. (Movies, night outside etc.)
This should be obvious, and has been stated already, but it bears repeating: TURN OFF DATA AND ALL OTHER MODEMS if you're not using them.
Thanks to all the devs and everyone who contributes.