From the Wilderness First Responder classes Patri and I took:

• Don't cough or sneeze on your hands.
  If you need to cover your face, cough into the crook of your arm or shoulder instead. Those are less likely to touch other things and people and spread germs.
• Wash your hands.
• Try not to touch your face.
  Touching something with germs and then touching your face is how you are most likely to get sick. Likewise, touching your face if you are sick and then touching something such as a refrigerator door or door knob is a way in which you are likely to get other people sick.

From something Patri was reading to me today: sinks and cutting boards tend to have more germs than toilets. Other germ hotbeds are as mentioned, refrigerator door handles, child play areas (especially ones at fast food restaurants and the like), and day care centers.

This isn't a big deal for most people, and in fact, one needs some cold exposure to build up immunity.

Obviously, I'm currently obsessed as it is a big deal for my little boy at the moment, as a regular cold can be deadly for a premie of under 2 years of age. A book Patri and I were recently reading said that half of young premies get rehospitalized at some point during their first year of life.