Another good one is to print up little cards that say "sorry I fucked up" "good for one free face shot" and carry the cards around in your wallet. When you find yourself blindsided by an argument hand one to your opponent. It doesn't even have to be your fault but it says you're more interested in keeping the peace than being right.
You might want to leave off the "face shot" part in your situation. That little firecracker will redeem.