1. Mimic the wall with a cut outs. Use a brown paper roll and trace the outline of each frame. Cut them out and tape onto the wall to map out where you'd like each photo to go. If you have a aviation in frames label each piece of brown paper with which frame was which so you don't get confused.
2. Create a mock up of which pictures you'd like to include. I took a picture of the brown paper frames taped on the wall and photoshopped what picture's I wanted in each spot. I was going for a "PNW/ West Coast" theme and wanted the wall to have a cohesive look in the imagery despite the variation in frames & sizes. This step was helpful when it came time to order the prints and making sure the print location correlated with the frame size.
3. Mix & Match VS Cohesive? Frame sizes, frame colours, colour photos vs black and white are all different variables when creating a gallery wall. As you can see I chose all the above having different frames, different sizes, coloured photos & black and white photos. I made all my photos that has a person in it black and white and kept the travel photos in colour. Depends what kind of look you're going for. I was going for eclectic. ;)
Did I miss any helpful tips? What theme would you choose for your gallery wall?