The wet foot test can help you determine if you overpronate or underpronate. Wet your foot and step onto an absorbent surface, like concrete or a piece of paper. Then evaluate the mark that your foot leaves:
If you can see an outline of the entire foot and it looks thick through the arch, you're an overpronator.
If the arch area is very thin or even detached from the mark left by the ball of your foot, you're an underpronator.
If the area through the arch is slightly narrow, you probably have normal pronation.