Powertop has a nice calibration feature.
first, run
# powertop --calibrate
After calibration is done, leave powertop running in a terminal for an hour, while using your laptop as usual. It will measure usage, and create a userprofile.
With the userprofile created, you can start powertop with:
# powertop --auto-tune
Add the last line to .bashrc or other startup location.