Socks should be made of cotton or other absorbent materials, and they should be changed frequently. You can take an extra pair of socks to work or school for changing during the day. Wear socks whenever you wear shoes. Shoes that have a noticeable odor are best thrown out if practical, although some can be salvaged by washing with a soapy detergent and bleach. Alternate shoes so that they can air out between uses, at least 24 hours if possible.
Leather usually breathes well, but ask a salesperson about the breathability of specific shoes.
Sweating and odor may be reduced by soaking your feet daily in black tea, which contains tannic acid. One method is to brew two tea bags in 1 pint of boiling water for 15 minutes. Then add the tea to 2 quarts of cool water and soak your feet for 20 to 30 minutes. Some people report great improvement after 7 to 10 days of daily tea soaks. If these measures fail to eradicate the odor within a few weeks, it may be time to see a doctor, who can prescribe stronger remedies.