If your tofu is water packed, layer your cutting board with a clean cotton towel and three layers of paper towels. Place tofu slices on top of the towels. Place a layer of three more paper towels on top of tofu, and cover with another cotton towel. Carefully place another cutting board or cookie sheet on top of the towels. Stack something heavy on top of the board, like a cast iron skillet, a large can of beans, heavy bowl or other weight to press down on tofu. Let sit for at least fifteen minutes, and up to one hour.