You need to chill that sucker down before you fill it. Pop it in the freezer to get it nice and cold.
Turn your CO2 pressure down very low (2-3 PSI) to minimize foaming and sloshing.
Ideally, get a bottle filler and modify it to work off of your tap. There are threads about that on here. They work well and allow you to fill from the bottom of the growler to minimize O2 and foaming.
Fill it all the way up. don't leave a lot of headspace or that's where your CO2 will end up.