Does anyone have any advice on how to airbrush a sunset?? I'm doing it on a 9" round....I've got very limited airbrush experience, and any advice would be greatly appreciated!!

Practice on some paper first. Look at a picture of what you want it to look like. Sometimes, the faintest of passes with your brush, with your finger barely on the trigger is what gets it to look nice. Here:

http://images.google.com/images?q=sunset&rls=com.microsoft:en-us&oe=UTF-8&startIndex=&startPage=1&rlz=1I7GGLL_en&um=1&ie=UTF-8&sa=N&hl=en&tab=wi

Which one is close? I can't really think of explaining step by step how to do it. It's just very light sprays with intensifying degrees of color. Hard to word it out for you.