Pick some of this up.
http://www.homedepot.com/p/Backyard-...N#.UlDkVl8o7IU
Use this for your base. Cut it down to fit the blind then you have a great background to start with. Dust it with some flat camo spray paint to knock the sheen off. Then you have something to stick natural brush in I used this on a blind this year and I just continue to add extra brush each trip, its getting better and better each time. One roll should be plenty for one blind. They also have it at Lowes and keep it stocked.