Trim Your Nails Short It might seem obvious, but keeping your nails short can prevent any gunk from getting trapped. "If you have long nails, make sure to wash the undersides well," Dr. Zeichner said. "Do not bite your nails. Putting your fingers in your mouth is a surefire way of transferring bacteria from your fingers to your face and possibly infecting yourself." Image Source: Getty / Sol de Zuasnabar Brebbia