Molds are found everywhere, indoors and out. There is no way to completely avoid them- but if you are allergic to molds, your symptoms will be better if you minimize your exposure to molds.
A HEPA air filter is helpful for minimzing all airborne allergens.
Molds grow well in damp conditions, so the places indoor molds may be hiding are the damp areas of the home: kitchens, bathrooms, laundry areas, basements. Clean these areas with a bleach-containing cleanser. Be sure to look at hidden areas of moisture- under the fridge (drip pan), beneath the sink, air conditioner condensation trays, etc. Make sure your dryer is vented to outdoors.
Be sure to use your exhaust fan in the bathroom to remove excess moisture.
In a damp or musty-smelling basement, a dehumidifier is effective in reducing mold counts.
Track your indoor humidity- ideally keeping it at about 40%- higher than this is encouraging to mold growth. In summers, air conditioning also dehumidifies the air.
Use pump-dispensed liquid soap rather than soap bars that can harbor mold.
Mold can occur in closed closets. Consider a chemical moisture-remover such as Damp-Rid.
Molds can hide in foam rubber and polyurethane foam- use plastic barriers to cover these.
Avoid gardening and lawn-mowing. These activities churn up soil-borne mold, increasing mold counts.
Since all moist soil can harbor mold, be careful with houseplants. Ideally there should be none in your bedroom or other areas where you spend a lot of time.
Avoid being outdoor in rainy, damp or foggy weather. These conditions cause many molds to sporulate (release their spores) so mold counts are typically high.
Molds are found in many foods. Opinion is divided on whether mold-allergic patients need to avoid food containing molds. You can experiment with removing these foods from your diet, and seeing if your symptoms improve:
breads made with yeast
soy sauce, vinegar
dried fruits like raisins
pickled meats and fish