Hi, I've been an airbrusher for 14 years. One of the best places to get guidance for airbrush is at the forum on

http://westcoastairbrush.com

They are very helpful. My suggestions are this. Using your airbrush, createx paint, 70 PSI on your compressor, practice all your strokes, gradients, circles, etc. on simple paper towels. Get the cheapy ones from the dollar store.

Keep practicing your alphabet and other designs until your stack of towels is at least 12". Then, post some of your best practice for critique on the above forum.

You will learn soooo much this way. It does help to get some airbrush videos to learn from too. Airbrush Action Magazine has alot.
http://airbrushaction.com
Good source of supplies:
http://bearair.com

Good luck!
Lynda
http://heltonart.50megs.com (airbrush pages being updated)