You can help to prevent athlete's foot by keeping your feet clean and dry. More specifically, you can try the following:
Wash your feet thoroughly every day and wear a clean pair of socks after your bath or shower.
Take time to dry your feet, including each toe, thoroughly (especially the webbed area between the toes) after you bathe, shower or swim.
If you use public pools or showers, wear thongs or sandals to prevent your bare feet from touching floors contaminated with fungi.
Choose leather shoes rather than vinyl, since leather lets feet "breathe" so they are more likely to stay dry.
Wear cotton socks to absorb sweat.
If possible, don't wear the same pair of shoes two days in a row. Give shoes a 24-hour break between wearing to air out and dry out.
Don't share shoes.