One rule is to never touch your face where germs can enter. Don’t poke a finger in your eye to wipe a tear or itch. Don’t poke a finger in your nose to pick or wipe. Wash your hands, wash your hands, wash your hands... Once you get home, wash your hands and use tissues to blot eyes and nose. That is the rule I follow.
Think that after going to a grocery or pharmacy, you enter your car and wipe your eye or nose. Don’t do it.
Grocery stores especially. That and my friends’ kids/grandkids is where I pick up most of the illnesses I acquire, it seems.
Don’t shake hands with people!