Identify and fix the moisture source (leaks, condensation, flooding, poor ventilation)
Dry the affected area completely (use fans/dehumidifiers; keep humidity below 50%)
Remove moldy materials that are porous or cannot be cleaned thoroughly (carpet, drywall up to a few feet, insulation, ceiling tiles, damaged wood)
Clean non-porous hard surfaces with detergent and water, then dry completely
Use appropriate cleaner for remaining mold on hard surfaces (EPA-registered mold remover or a solution such as diluted bleach if appropriate for the surface)
Never mix cleaning chemicals (especially bleach with ammonia or other products)
Wear protective gear (N95 or higher respirator, gloves, eye protection)
Keep people and pets away from the work area
Ventilate the area during cleaning (open windows/doors if safe; use fans that vent outdoors)
Bag and seal moldy debris before disposal
Thoroughly clean surrounding areas and tools after work
Wash reusable items with detergent and dry completely
If mold covers a large area (about 10 sq ft / 1 sq m or more) or keeps returning, hire a professional
Seek professional help for mold in HVAC systems, sewage/black-water contamination, or if anyone has high-risk health conditions
Do not paint or caulk over mold without cleaning and fully drying first