More of a household tip, but if school permits more than one colour socks, dc1 has all navy, dc 2 all black... if school allows white or red, white or black... always buy not-white.
Anybody who gets me up before 8am on the weekend can expect to help me do the dishes, tidy the house, get some extra times tables work in... anybody who quietly helps themselves to a banana and a glass of milk and plays in their bedroom until 8am gets left alone.
If you want them to practice spellings 3x, say you want 8x, if you want them to fold the laundry, say you want folding and ironing, if you are allowing 3 sweets, say you are allowing 1. Leave room for compromise, so they feel they can win a little bit. They'll happily do what needs doing whilst thinking they got off lightly.
When leaving a party or playground, find other parents who are also leaving, and go with a "wave". Look, DS, everybody is going, Jimmy, Sam and Nat!
And pick your battles, is that one glass of coke or lolly really going to be such a problem? Can you really not stay for another ten minutes?