We do a traditonal foods types diet (whole foods, broths, ferments, high vitamin cod liver oil, sprouted breads ect for maximum nutrients). Coconut products (like oil) are also great for the immune system.
Fresh air, rest, sunshine, and lots of cuddling and nursing

Reducing stress (here that means little or no TV, no packed schedules) and having healthy relationships.
During illness
Sambucol immune system syrup for colds ect
Sodum Ascorbate
Extra hv cod liver oil
Extra zinc
Not medicating fever
Prayer, back rubs, humidifier
Homemade chicken soup
But I don't have to use these things too often. We found a great naturopath who raised her children the same way we are. It is wonderful to have someone who can check out your kids and not automatically hand out a script for abx!