Under painting is your friend
Some of the trick I learned while working at WDW
was under painting.
So I needed to repaint my helmet-Last time it was painted was 1999
Cleaned it up with Denature Alcohol-
Sanded- rises under water- dry and ready
first coat Krylon Silver.
Key to making things shiny with metal paints is smooth surface
Let silver dry for about 30 mins and start masking off and doing more base coats of other colors-
Now when the paint of the other colors (greens) is still some what tacky you can scratch it with a wire brush lightly and I like to take used rubber gloves and roll them on the surface. What happens it sticks to the tacky paint and exposes the underpaint when pull away.
My colors are with the intent of Jedi but dont have to be dead on to the movie (it was just a small amount of time we saw Boba in it who knows what his helmet looked like before or after that hehe?)