Logs and pine needles...
If you have the time, do a quick google for snipers hides. There are field manuals after field manuals on the proper type of hide. Specifically FM20-3
Ideally, you would find a low depression in the ground or behind some natural cover. Dig out enough to where you can lay prone comfortably and still maintain situational awareness. Using found materials from the immediate area (this helps maintain color and keep the enemy from noticing that "new" pile of sticks) you need to construct a nice "blind". If you don't need to worry about sighting from behind or above, just make a small wall of sorts that you can shoot through. Remember... any straight lines... perpendicular angles or unnatural shapes will give you away.