Brilliant! You put toothpaste on the picture's hanger, eyeball where you want your picture hung, press against the wall, then place the nail in the toothpaste spot on the wall. Wipe off toothpaste and hang picture! Brilliant!!!
How to hang up a gallery photo arrangement: Lay out your 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.
Every January turn all of the hangers in your closet backwards, like this. It takes about 60 seconds: Each time you wear an item, hang it back up in the normal fashion, which takes zero effort to remember or do. In June, any item that is still hanging backwards has not been worn in 6 months, donate it to Goodwill unless you can come up with a good reason to save it.