“To hang your display, try laying all of the photos out on a table or floor within an area that’s about the size of your wall space. Rework the arrangement until you are satisfied. Use self-stick notes to number the pictures and make a sketch of the layout. Or, like the photo shown here, cut out paper in the shape of each frame and tape these up on the wall before installing the picture hooks.” ~ from Better Homes and Gardens

So I did this, but still managed to screw up a little. My recommendations:

1) If you have a light colored wall, use a dark colored paper

2) Be really sure about your frame/mat selections before doing the paper thing. After snapping this photo I said, “Oh, snap.” And then switched out the middle frame with another that was matted. It looks much better now. This changed my spacing, but I didn’t move the side ones.

3) Nail up a few frames and then adjust – don’t do it all at once, that way you can fix mistakes (like point #2). That bottom row? It’s now spread out much further – the two ends actually are about 2 cm wider than the top row. SO much easier to do when it’s paper and not nails all over my beautiful stenciled wall.

4) Do the tape so it’s hidden – I kept getting distracted by the BLUE tape and it obscured the edges for lining things up.

Original source: Better Homes and Gardens via a popular Centsational Girl pin.
Difficulty (1-5): 2    You have to use scissors, people. Wear your safety goggles.
Result (1-5): 4    I still had to make adjustments after, but that was user error.