Stay Dry and Loose
Yeast organisms like warm, moist conditions, with little or no oxygen. In order to deny them the perfect growing medium, dry your vaginal area thoroughly after bathing or showering.
Opt for "breathable" cotton underwear and loose pants, and, if you must wear nylons, choose those that have a built-in cotton-lined panty. Also, avoid lounging around in a wet swimsuit; change into dry clothing as soon as you're done swimming for a time.