The easiest way to hang a picture on a wall- use toothpaste to mark where the nail goes, then press against your wall and voila! Perfect for hanging a collage of pictures- no measuring and marking required!
Genius...Lay out your gallery arrangement. Flip frames over. Mark hanger/nail spot on several pieces of wax paper taped together. Flip waxed paper over, tape to wall, Nail into wall where indicated. Remove waxed paper. Hang photos.