If you have the money a webtex consealment vest are supposed to be the best:
http://www.outdoorgb.com/p/web-tex_concealment_vest/
I personally didn't use netting. I took a woodland jacket and went to Andy n Bax on got 3 yards or so of their sack-cloth type stuff. Then cut into strips about 2 inches by a foot. Dyed them in brown and green and left some plain, glued them all on and took out the cross sections. Also while your at joans looking for the dye, pick up a couple feet of thick and wide elastic strap to glue on for veggie loops.
For more information, I would make an arniesairsoft.co.uk account and check under their sniper section. They have ALOT more information and a dedicated guillie making thread.
Good luck! (and have patience)