"Sterilize, sterilize, sterilize," Dr. Torres says — it's the surest way to prevent infecting your skin with harmful bacteria. "Wash your face or area where you are applying the makeup to make sure you don't have any bacteria there that you will trap with the makeup. It might get trapped close to your skin and create irritation."
Your hands also must be clean, or you risk spreading germs to your skin and makeup. We all have those mornings running from the blow-dryer to the microwave to the computer and then back to the bathroom to do our makeup. Just try to keep in mind that if your skin and hands are clean every time you touch your makeup, the chances that you'll contaminate a product will drop dramatically.