I did a H&R shotgun. I pulled the stocks and scuff sanded them, then I laid down a base coat of a light brown. I used a coathanger to hang the wood until it was dry. After it dried, I laid in light stripes of black. I didn't get real serious about stencils or anything like that. The idea was only to break-up the outline. After the black stripes dried, I kind of held the spray can WAAAY back and laid a light mist of black on it, just to kind of darken it up a little. The light/dark pattern blended well into the woods where I hunt.
I'll point out a problem that I had. After carrying the gun on a sling for a season, I noticed wear points where the gun rubbed on my knife or something else on my belt. It wasn't anything serious, but it marred the paint job. I'd advise a good clearcoat over it all for protection.
I've heard that leaves and sticks and things make pretty good stencils for camo patterns if your going that route.
