Great tip from Better Homes and Garden, found by way of Lifehacker.
Hanging pictures on a blank wall can be rough, especially with all of the hit-and-miss involved in aligning your frames and hammering in your nails. Better Homes and Gardens has a tip for getting your wall hangings right the first time so you don’t end up with three holes side by side while you attempt the perfect hang.
1. Trace pictures onto brown kraft paper and cut out. Label each of the papers with a description of the picture or a corresponding number.
2. Using blue painter’s tape (which won’t pull up wall paint), tape the papers to the wall. Experiment with arrangements until you have one you like.
3. Install picture-hanging hardware directly through the paper. Pull paper away and hang pictures one by one.
The third step is the real kicker; by installing through the paper, you should have a much better idea of exactly where to put your nail than you do when hanging without the paper.