The best way I've found to prevent strawberries from developing mold is to use a vinegar rinse. Vinegar kills the mold spores hiding under leaves and on the surface of the berries. I use the basket and bowl of my salad spinner to rinse strawberries but a colander and a large bowl will work equally as well. Add 1 part vinegar to 3 parts water and soak the strawberries for 5 - 10 minutes. Drain and rinse with cool water, then lay them out on a towel, pat dry and let them dry completely. I line a lidded glass dish (or even the clamshell plastic package they came in) with a paper towel and store them in the fridge. Rinsing strawberries in a vinegar rinse extends their life significantly, by a week or longer, depending on how fresh they were when purchased. They won't taste like vinegar!