I took the plunge and finally bought an airbrush kit. I haven't had many problems so far, but I've been painting a rather large area on a model that I bought andI can't seem to get an even coat with the paint. I've been using an enamel paint, and my airbrush is dual action, gravity feed. I've already gone over it a couple of times with the paint, but each time I can't seem to get rid of the unevenness. Can anyone tell me what I'm doing wrong, or if there's anything I can do to fix it?