Practicing good hygiene and avoiding exposure are the best preventive methods.
Sneeze or cough into your sleeve, rather than your hand, if you do not have a tissue. If you do have a tissue, cover your nose and mouth with it when you cough or sneeze. Place, rather than throw, the tissue in the trash after you use it.
Wash your hands often with soap and water, especially after you cough or sneeze. Alcohol-based hand cleaners are also effective.
Avoid touching your eyes, nose or mouth. Germs spread that way.
If you get sick, the CDC recommends that you stay home from work or school and limit contact with others to keep from infecting them.