I also cut my teeth on 1/72nd plastics with home-made rules. We always had to repaint them after every battle since the paint flaked off though. I guess the new plastics are stiffer?
I painted most minis with enamels back then, but he minis do have to be washed with a detergent, and then rinsed thoroughtly before priming.
Basing the minis also helps, as you don't have to touch the critters much after that.
1/72 still is rather soft plastic, Hät a bit stiffer that the average.