txswat,
I use Testors Military Flats model paint, with 3-4 coats of clear flat lacquer afterwards. It holds up well, and can be completely removed with Hoppes(with a little elbow grease). I would just spray the base color(usually the lightest color) and then use a brush for the rest. You get better definition this way rather than spraying all the colors. They tend to run together without the benefit of breaking the outline as well. Its actually pretty easy to paint your guns, although the first ones always the hardest. You can get cheap stock sets from Northridge for the AR. Makes experimenting fairly pain free, and you dont have to clean up your good set if you screw up. They sell the sets for $20, thats stock, handguards and grip. They are off M16A1's so they have the shorter stock and triangular handguards. I'd just get the cammies you want to copy and use them as the pattern and go from there. I usually do the whole gun, I havent decided what camo I want yet, thats why the metals not done on mine. I'm leaning towards the Flecktarn.