I was using Safer 3 in 1 spray, but stopped because I wasn't sure if it worked and it smelled like crap. I'm not sure how to avoid mold. I've heard that it helps to keep plants covered from the rain, but I already found a small patch of mold in my plant that has been in the greenhouse all year and never gotten wet, so who knows. Also morning dew gets the outdoor plants pretty wet everyday, rain or no rain. So the goal is to keep your plants as dry as possible, but keep air flowing, pretty hard to do outside, good luck.
As long as the mold doesn't get out of control, just toss or make hash out of any affected bud at the end of the year. And cut any rotten buds off your plant as you find them.