I went thru a lot of my stash before I decided on mine. I took pictures and put them on the computer to help me figure which ones needed to be moved or eliminated. It's funny, something you might think would be perfect next to one looks better further away. If you can, cut 1 strip of each color you want to use and lay them out, rearrange if needed. Lots of pics. There should be some variety in color, such as light to dark or medium to dark. Pick a couple of options for the triangles or squares (whichever pattern you choose), then start working off of them. I think a larger print looks good for the ones with center squares. You will likely change your mind a few times. The book recommends waiting on the separator strips/borders until you are done with the braids. I did change my mind on the narrow part of the separator strips from my original plan. I'm very pleased with how mine came out.
Another thought is to buy a jelly roll and work with that.