There have been many recent cases of sick buildings with "black mold" as well as other types of mold that thrive on wet drywall and other materials. Severe mold contamination may require a mold remediation company to clean up the property and remove mold. In some cases, the property may be uninhabitable.
On a daily basis, however, there are some basic steps to avoid mold in your home:
1. Immediately address any leaks, no matter how small, in your roof, bathrooms, kitchens, or any other part of the home. Replace any drywall or wood that shows signs of mold.
2. If you have a central ventilation system, have the vents cleaned periodically (I have them cleaned about every 3 years) to remove any mold-spores as well as dust and particulate build-up.
3. In humid climates, use a dehumidifier, especially in basements.
4. Use vents in bathrooms or other areas where there is regular moisture.
5. Use bathroom squeegees after each shower to remove excess water from the shower stall to prevent mildew.
6. Make sure water drains away from the house at least several feet during rainstorms. A properly installed gutter system will help prevent standing water from accumulating around the foundation.
7. Opt for smooth floor surfaces, such as tile, rather than carpeting that can accumulate mold spores.
8. Use HEPA air filters in your home.
Some useful links: