These are simple to wear.  It's like slipping on sandals but not having the too "laid back" sandals look!  I normally wear a size 13 for Asics running shoes and Nike basketball shoes.  I ordered these Sanuk in a size 13 and I they fit ok but they might be on the larger side.  I would try a size 12 next time.  If you like it a little loose, I'd recommend purchasing the same size as you would for running shoes.  I'll be getting another one in a different style and color soon!