Buy NON-LATEX condoms. Latex irritates a lot of women, which will in turn cause a yeast infection. I recently bought the lubricant 'O'My' off the internet, it is made with Hemp. Says it helps prevent yeast infections. If you can't find the type of condom you want in stores, have you tried buying them online??
Eat lots of yogurt too. I take acidophilus, eat yogurt, and right now I'm battling an infection so I'm using yogurt suppositories I made myself. I put them in non latex rubber gloves and frozen them. Then inserted the frozen yogurt at night. I feel much better. The doctor gave me diflucan, I took 2 doses before I finally started relief.