#1: use only one "power saver" app. Running two (or more) simultaneously will cause conflicts and may well run your battery down quicker.
#2: Go through your installed apps with a fine toothcomb, uninstall any you don't use, and check the settings in those you do e.g. do you really need Twitter/FB/weather updates every 5mins?
#3: Use wi-fi whenever you can.
As for modifying the CPU settings, that requires a custom kernel such as Siyah or Dorimanx, a suitable app (STweaks, SetCPU etc) and a lot of testing to find the optimum setup for your particular device.