I used Rustoleum camo paint from Walmart on mine, just the green though, I didn't opt for the brown and black combo. I bought a quart and thinned it enough to spray. Mine had some old paint still on it and a few bare spots that I painted with aluminum primer. That paint has been on that boat now for over 5 years with no signs of lifting, peeling, fading or even much wear except for the corners where the straps rub it on the trailer. Prep is the key.
If you want a pro look and you're not strapped for cash a yinyl graphic may be another option. Here's a link but there may be cheaper options.
Real easy to do. Pick your colors and pick a pattern and just go for it. Camo should be flat and not reflective....... and Nat'l Guard units in your area? The military camo paint is the best there is and trust me .... you don't want to know the price....... but every shop may have a can or two laying around that they would give away. The military has changed it's camo colors so there is paint out there.
I saw one where a guy used stencils and it turned out great. I think he bought the camo stencils, but I don't think it would be that hard to cut them out yourself.