To keep your feet from sweating throughout the day wash your feet using antibacterial soap and be sure to wash real good in between your toes too.
After you wash your feet thoroughly then dry your feet out thoroughly as well and apply some cornstarch to your feet.
You can also use foot powder or other antifungal powder as well to keep your feet from getting sweaty.
Another thing you can do to keep your feet from sweating is to wear wicking socks that are made from natural or acrylic fiber blends that draw the moisture away from your feet instead of trapping it so that your feet will not sweat.