Wash Your Hands. Another of the most effective ways to prevent colds and the flu is simply washing your hands properly and frequently. “Wash your hands a lot, and encourage those around you to wash their hands,” says Nancy Elder, MD, associate professor and director of research in the department of family and community medicine at the University of Cincinnati in Ohio. This will help to get rid of cold germs you pick up from doorknobs and stair rails, and keep you from getting them into your body. One study found that college students who washed hands frequently had fewer cold and flu symptoms.