May I add another observation. I own a sign company, do air brush on signs and vehicels etc. etc. I have all the equipment and a place to do it. However you don't need all that to do some pretty darned good camo paint jobs.
I suggest that before you invest in several hundred bucks in paint and equipment, you just buy some cans of spray paint in camo colors you think you'll like. Then get a plain old 2x4 about 3 feet long and practice painting it a few times.
Get a base coat, probably a lighter color.
Tear a piece of cardboard into an irregular shape with a couple of sharp curves in it. This is a cheap and unique spray mask.
Hand hold that cardboard on the wood and spray darker color accross the edge of the cardboard and fade the color out to nothing as you spray father away from the mask.
Move the cardboard a few inches away from where you just sprayed and repeat the porcess.
By moving the mask several inches one time and only a few the next, in random order, you can end up with a very peasing effect.
Thats about as simple as it gets. And if you screw it up, no sweat. Put on another base coat and try it again. Play with the colors. Have fun. When you get a little confidence, try it on a gun. Still use the cheaper Krylon or Rust Oliem or what ever is on sale at Wal-Mart...
When you get good at it, and if you really like to do it, THEN invest some equipment and the better coating products.
Semper Fi .... Mark