Try Krylon Camouflage spray can. Easy to do, easy to change at any time to suit your environment. If you want it to last longer, use a flat clear.
If you want something tougher with a little bit of texture, use duracoat.
Take a look at some good paint jobs and tips here: (you can see the one I did last winter, bottom of first page)
Rifle Painting Tutorial
And some more here: (you can see the one I did this spring, bottom of second page)
Krylon Camo Pics
Just make sure to cover everything you don't want painted (sounds dumb, but I've seen guys paint their scope's turrets) and don't be afraid, Krylon is easy to use and imperfections can be covered or painted over. However, I have no experience with duracoat so I can't help you much with it.
Come back with pictures, and have fun! =)
EDIT: And if you really want texture, try Marine Tex
Stock Texture