Create your wall gallery on a large poster-sized paper before you starting hammering any nails into the wall. If your wall space is large, tape a few pieces together.
1) Lay the paper on the floor and place your frames in the arrangement that you want.
2) With a pencil, trace around each frame.
3) Dot the place where you will be placing the nail. Use a measuring tape to evenly place the dots so they are in the same line on each plane.
3) Number the boxes on the paper and the frames so they match up.
4) Remove the frames and tape the large paper on the wall.
5) Hammer in the nails where the dots are (through the paper).
6) Once all the nails are in place, gently rip the paper off the wall and hang your frames.
Now you have an even art gallery that looks amazing and saved you tons of time asking someone else "Does that look straight?"
Check out more wall gallery ideas from Apartment Therapy:
(Image from How Do You Choose Your Art Gallery Layout?)