Seems like a simple one, but many people don’t follow this advice closely enough. WebMD says you should think like a doctor, who may be exposed to cold and flu viruses multiple times a day (and so can you).
Wash your hands with warm water and soap for at least 20 seconds regularly throughout the day, suggests the source. You can also try carrying hand sanitizer with you if you don’t have regular access to a faucet. Use a paper towel to turn the faucet off, or you could be ending your hygiene ritual by picking up more germs.