Reduce Indoor Humidity
Humidifiers, long showers and clothes dryers can all contribute to excess moisture in the air. Cooking, and even breathing, can increase moisture levels. To reduce the humidity in your home, make sure clothes dryers are vented outside of your house, use exhaust fans in bathrooms and kitchens and occasionally open windows to let your home air out.
Storm windows are best at preventing mold and mildew growth. If installing storm windows is not an option for you, there are other steps you can take to update your windows. Caulk around your windows to help keep the glass warmer. Warmer glass results in less condensation and less mold and mildew. Increase air circulation around the window by eliminating heavy window coverings.
Reduce Food Sources
Organic food sources such as skin cells and pet dander are commonly found in household dust. Mold and mildew need this food to live. Every house has dust, but frequently dusting your windows will remove much of the organic matter that mold feeds on. Damp cloths and electrostatic dusters are the best choices for dust removal. Other methods may simply move dust around. A vacuum cleaner with a HEPA filter will also remove fine particles from your home.
Manually Remove Water
Manually remove window condensation with a cloth on days when it is particularly heavy. Moisture on windows that face north, or spend much of the day in the shade, may not evaporate easily. When the outside temperature is cold, condensation may be a real problem on windows. In these cases, it may be necessary to wipe the moisture away from time to time.