Tips
It's all about the water
Mold is everywhere, and it can grow anywhere. Even if you've never had a mold problem before it is good to keep a dehumidifier in the house. I'm not going to recommend any specific brand names. The key features to look for would just be the unit having a digital humidity reading with programable settings, and make sure its rated for the square footage of your home or higher. You will know you need a second or a bigger one if it never shuts off. Below 50% humidity is a good setting. (maybe 47%)
If there is mold growing then there has to be a liquid water or humidity source. Check behind and under all appliances, sinks showers, and hvac units.
The pattern mold grows in can tell you a lot about the cause of the problem.
In the top three pictures you can see that the growth pattern is sparse and scattered. This is usually from humidity.
Water is heavy so some people assume that humid air sinks, but it is actually less dense than dry air so it rises. This scattered growth pattern is usually seen at eye level or higher because the humidity rises.
In the lower three pictures you can see that the growth pattern is much thicker and tight. This is indicative of a liquid water intrusion or a leak. This growth pattern is usually seen lower as gravity pulls water down.
