Vent bathrooms and clothes dryers to the outside. Do not use humidifiers. Trim back trees and shrubs around the house to reduce shade. Remove debris from your yard, roof, and gutters. Clean mold and mildew growth from walls with water mixed with chlorine bleach, diluted three parts water to one part bleach.
Commercial products can also remove mildew and mold.
Follow product instructions carefully. Very moldy items should be replaced. Change heating and cooling system filters monthly. Vacuum air return covers or screens regularly. Check air conditioners for mold before each cooling season and have coils cleaned as needed.