I found crocs to be awful as there wasn't enough support in the arch. They are sure cute, though!

The best thing, as the others have said, is stretching and shoes. Another stretch is to stand facing a wall, about arms-length away. Put your hands on the wall, about upper chest height with one foot with toes almost up against the wall, knee bent, while your other leg is straightened out behind you. Then lean into the wall bending your elbows. Hold for a count of ten, if possible, and feel the stretch in the back leg. Repeat after switching legs. (Well, I know that reads funny, but it's hard to describe!)