@GeneralHandGrenade:
I didn’t use primer but I don’t really know what I’m doing though. I washed the pieces in warm, soapy water then dried them thoroughly. I found the best way to paint them was to lay them all face down on a piece of cardboard and spray them as per directions on the can. After about 10-15 minutes I moved them to a drier part of the cardboard using a toothpick to keep them from sticking to the surface. After about 2 hours I flipped them all over and painted the other side again moving them with the toothpick.
While I haven’t painted anything for Axis and Allies (due to the fact, I’m still kinda stuck on OOB units and nobody to play against)… I have been active in customizing Risk (classic) and Risk: Lord of the Rings Trilogy Edition… yea… not Axis and Allies, my true love, but at least I can get my kids to play Risk with me (they’re getting quite good at it too). I have, oddly enough, done a lot of custom work for those games, painting capitals for classic Risk and Fortresses and Oliphants for LotR Risk… so painting multiple units of tiny size is something I’m kinda used to.
Here’s some tips you might find useful painting multiple tiny units on a mass scale that should save you some time and headache with the “paint on one side, then flip over with toothpicks and move to paint again” issue you described.
I paint all sides at once, because what I do is lay down some strips of masking tape, sticky-side up, the stick all my tiny units “standing up” on the sticky masking tape (I then tape the masking tape down to my painting surface so the tape doesn’t move either)… this keeps them from falling over during painting, but I can spray them from all sides in one go, without having to flip them with toothpicks… they just don’t move when stuck to masking tape, and they easily come off the masking tape when dry.
Here’s a couple of samples of how I tape-up some units (before and after applying some primer paint).