Howto save battery?

Saving battery is easy: Just turn on airplain mode...
... but that is probably not what you want! Saving battery is hard, it depends on the device, the user (i.e. how you use you device) and a lot of cryptic settings. Both statements are true to a certain extent, but in the end tuning your device is just some work and experimenting with the settings.
The following hints might help you.

• Switch off the services you do not need.
  Some services like wifi, bluetooth or GPS use quite a lot of battery, if you do not need them switch them off (manually preferable). If you use your wifi only at home switch it off when you leave your home.
  
• Avoid excessive service switches.
  Switching a service costs battery if you switch a service each time the screen goes off, this might cost more battery than it saves.
• Start with the default settings of cpu tuner.
  If you got a feeling for how much battery it uses, change one thing at time.
• Use the governor thresholds not the cpu frequencies.
  E.g. a ondemand governor with a up threshold of 80% yields a fast but rather battery draining configuration, where as a conservative governor with and up threshold of 98% and a down threshold of 90% is a battery saving configuration which makes you device a little slow.
• Do not trust any readout only trust the battery live.

For more insights on saving battery read "make your Android power efficient in any situation" and "on tweaking cpufreq for Android devices". Have fun experimenting...