inspection
It is important to locate where the problem is coming from or what is causing the problem.
treatment
It is important that nobody is inside the building specially kids under 12 or 65 + years old. For safety reasons at least 15 to 30 minutes before you can get into the house depends on what kind of treatment.
observation
If needed to come back after 4 weeks of treatment based on the infestations.
prevention
Sometimes it helps a lot if sanitation is applied.