(Info from Grandparents.com)
Wash and rotate socks and shoes
Needless to say, your socks should be changed every day to prevent the buildup of moisture and dead skin —sometimes more than once, if you’re particularly sweaty or it’s really hot out. To ensure they’re cleaned all the way through, turn them inside-out before throwing them in the washing machine.
Shoes are a bit different. Certain pairs can be washed on occasion without doing damage to the materials—simply read the care instructions and make sure they dry completely—but many cannot. Either way, it’s important to rotate shoes daily, and air out used pairs. "Try not to wear the same pair of shoes two days in a row," says Dr. Kosinski. "And at the end of the day, don’t throw your shoes in a dark closet. Instead, allow them to air out in a well-lit, ventilated spot."
Dr. Schwartz concurs, adding: "Dry shoes as soon as possible if they get wet or damp."