Follow these steps every time:
Cover your mouth and nose with a tissue when you cough or sneeze. Put your used tissue in the wastebasket.
If you don’t have a tissue, cough or sneeze into your upper sleeve or elbow, not your hands.
Wash hands often with soap and warm water for 20 seconds. If soap and water are not available, use a 60% alcohol-based hand rub.
How to Safely Cough and Sneeze (WebMD)