I love lightning bolts, for a while it was my favorite doodle, pick your own favorite doodle and go crazy with your shoes. I have about 9 pairs that I made all within a week, and now I wear them with coordinating outfits.
Find a pair of canvas shoes or slippers that you like, pick a pretty color, and try them on! It's no fun when you get the wrong size.
Buy fabric paint in whatever colors you want or if you have it already pick the colors you like.
have fun, don't be afraid to do something wacky! I have a pair that say Bling Bling. they are the blue ones. I wear them the most.