Well, the best way for a beginner would be to take a cheap brush and dip it in a metallic paint. Then you need to try to dab off as much paint as you can using a paper towel. There will still be a little bit of paint left and that's what you use on the gun. The guns I do probably have 4-6 layers of very thin paint. this gives it a random and natural look (when successful!) They also sell pigment powder that you brush on and then have to spray with a clearcoat to seal it in. It's harder to work with, but until you spray the clearcoat on it, you can wipe away mistakes with a wet towel and let it dry before trying again.