I flush the system.
Then refill half of the total coolant volume with straight coolant.
Make sure the heat is on full.
Then top it up the the "min." line with distilled water.
Run the engine with the cap off up to operating temp. according to the gauge.
Shut the engine off and let it sit for 15 minutes (you can grab a beer at this stage)
The thermostat will open while you're waiting and trapped air will come out.
Restart the car and fill to the max line.
Go for a ride.
Check the level.
Done.
Enjoy the rest of the beer.