Preventative measures are the best in my opinion. I run an all natural preschool and we follow this method when the cold starts to set in.
1. Wash hands often, I can't say this enough. Everyone should be washing before and after they eat and before and after playing with toys.
2. Elderberries in your diet. I make elderberry tea from dried elderberries for snack every day! It is an immune booster that is safe and healthy for children.
3. Garlic in your diet. We have garlic added into our lunches.
4. Eating healthy whole foods. Lots of fresh veggies, seeds and nuts, beans, whole grains (like brown rice, quinoa, et cetera)
If and when they do become congested: saline spray to clear out their nasal passages, eucalyptus in the bath, humidifier at night in their room.
This has worked out very well for my children and myself without resorting to treating the aftermath of getting a terrible cold.
My daughter has gotten croup twice (once each winter) and hot steamy bathrooms worked for her to breath well. Once we had to go and get a nebulizer treatment. But other than that she had been healthy. No ear infections, or normal childhood issues except for the two croup issues.
For my family and myself, I make an elderberry syrup that we take each day in the fall and winter months. One tablespoon dried elderberries to a half cup water, boil gently on the stove with a lid for 10 minutes, let sit for 10 minutes, add local raw honey to taste sweet, put in a lidded glass jar in the fridge and take a 1/4 cup or more each day. When you feel a cold coming on, take about 1/4 cup each hour all day and the cold either doesn't amount to anything or you get a little congestion. Keep taking it whenever you can remember while you are congested.
I hope this helps.
P.
Edit: I would also like to add that the flu shot doesn't always help. We never get flu shots because when we have gotten them, at the request of our old doctor, we ended up being sicker over the winters. It has worked well for my friends son who is asthmatic in the past but he has been regularly seeing a chiropractor and no longer has asthma issues...something to think about.