I wear a woman's size 9. Sometimes "wide" shoes are more comfortable, but sometimes they're too wide. I've tried 9.5, and they're too long; my foot slides back and forth.
In men's, I take a size 8. However, in guy-mode I wear white athletic socks -- once a nerd, always a nerd. 🙂 In gal-mode, I wear stockings or knee-highs (duh!). That probably accounts for a 1/2 size difference.