You don't want to get sick and I don't want to get sick so I'm gonna tell you how to best avoid the flu. I've numbered these in order of importance.
1. Get a flu shot. This is the greatest step in flu prevention, but it is not the only one and does not guarantee that you will not catch the flu. This step is especially important if you have a weak immune system, have long term breathing problems, or are a senior citizen.
2. Wash your hands often. Wash before you eat and after you cough, sneeze, or blow your nose. Use a Kleenex and throw it away right after you are done. Even if it is only allergies act as though you are contagious. If there is not soap and water available then use an alcohol based hand sanitizer.
3. Stay home if you are sick. Stay home until your temperature has been normal for 24 hours without taking Tylenol or other fever reducers. You can spread the flu from 1 day before you have symptoms to 5 days after. If your child is sick, then you are carrying the germs with you. Be considerate of others and keep the germs confined.
4. Be mindful of what you touch, in fact, don't touch it if possible. Try not to touch your face (that's especially hard to do when you're thinking about it) because that is the easiest place for flu germs to infect. Handrails, door knobs, money, counter tops, and shopping carts- they are all very, very dirty. If you do touch a public surface, go back to #2.
For more info about how to tell if you have the flu and what to do about it visit the Centers for Disease Control's flu page.