I heard that a bath with tea tree oil can help prevent thrush. Has anyone tried tis or know other natural remedies?

I wouldn't bath with it as it can be quite drying, but some women do use a bit vaginally to treat not necessary prevent and it is not something you would probably want to use on a regular basis.

Many women find yogurt works as well... eating the probiotic yogurts are apparently even better than the standard yogurts. Just eating several servings a week, along with the usual recommendations of avoiding very tight clothing, avoiding too much mositure, etc. helps to prevent yeast infections.