just getting started, what do i practice?

Check out the Testors online guides:
http://www.testors.com/hobbyist_guides.asp
Chapter 06 is great, and is just what you're looking for. It will explain all about different strokes, effects, etc.

i think the basic hand movment is just back and forth,

Just practice airbrush control of thick and thin lines from varying distances.
You can spray small circles also if you want to learn control. If you can set the model down as you paint it is better as holding the airbrush with two hands allows better control than using one.

This should get you started at least.

Mike