Anything probably that is specified as "woodland camo" would work. Digital camo will work as well, just as long as you don't get something crazy like desert camo or something for a woodland environment. Gander Mountain, Cabela's, or any store with a sporting goods section with hunting stuff will have what you are looking for. You won't need anything too expensive because unless it's a heavy woodland area, then the other people will see you anyways.
Other than a ghillie suit.. Digital? Keep in mind that paintball combat range is alot closer than the real thing. Therefore you need to find camo that has smaller blobs or colors.. The army use to use woodland and they had a certain size of print for the average range of combat... from far away the camo tricks your eyes and blends the enemy into there backround.. But for paintball, the combat range is closer so you need smaller camo. (print) Hunters camo has bigger blobs of colors too because, Hunters shoot at far distances so there camo needs to be bigger. Again Paintball has closer combat ranges so the camo needs to smaller to be the most effective.