One of the greatest factors of preventing black mold is the humidity level. If you have high humidity in your geographical region you should always be cautious of hidden mold spores.
A relative humidity level over 55% greatly increases the chance of toxic mold growth. Having a relative humidity sensor in certain areas of your house will help you monitor the environment which mold is likely to grow.
If you notice you do have a high humidity level it is a good idea to run dehumidifiers and perhaps air purifiers if mold is present. During the summer, in high temperatures, you may notice a mildew smell, especially if your air conditioner is not running. This could be due to mold in the sheet rock, sub floor, carpet, carpet padding or many other areas.