You need to fine tune your stroke. Start before the area your painting and shut the gun off after you pass the area you are painting. Smooth and even passes with the gun using the same speed with each pass, making your overlap the same also.
Like they said, metallics are not forgiving.
Lite colored areas represent less paint,or dryer spray,darker areas are more paint or shot wetter.
When metallics are shot dry the metal stays up, if shot wet the metal will sink exposing more color, hence the light/dark results.
I know it's sometimes hard to determine how the paint is laying out, so make sure you have good lighting so you can see how the paint is going on. Position your lights so reflected light allows you see the surface.
Keep the angle of your gun the same. You can lay paint on a flat surface easier than a vertical surface, meaning you can put more paint on a flat surface and get away with it, doing the same to a vertical surface may render some runs or curtains in the result.
Practice, very few people are born with the talent to paint.
Dan
