Wash your feet with an antibacterial soap once a day.
Change your socks (ideally wool or cotton, not nylon) at least once a day.
Keep your toenails short and clean, and remove any hard skin with a foot file (it can become soggy when damp, which provides an ideal home for bacteria).
1. 8 Ways to Keep Your Shoes Stink-Free During No-Socks Season by Dwyer Frame
2. How to prevent a smelly feet by ABIGAIL MALBONAbbi coined from PrimaBlog