I've been meaning to share this idea with you. When I was teaching at the NC Quilt Symposium earlier this year, I met a woman with painted shoes. That she painted herself!
Turns out she taught classes on shoe painting and one of her students was there. Here's her shoe:
I'm a little fuzzy on the details but as I recall they recommended black leather shoes. You need to scuff up the finish so the paint will stick. Use acrylic paint and put a finish on them when the paint is dry. They said it was a great thing to do to a shoe that was showing some wear. I have some Birkenstocks that I really need to paint.