Clean refrigerator drip pans regularly according to the manufacturer's instructions. If your refrigerator and freezer doors do not seal properly, moisture can build up and mold can flourish. Remove any mold on the door gaskets and replace faulty gaskets.
Properly insulate and ventilate the attic of your home.
Periodically inspect attics after snow has fallen to ensure no snow has entered your home through roof vents or other ways.
Clean up and correct any water problems in your basement as quickly as possible.