For prevention, eat enough citrus fruits and raw vegetables. The best natural antibiotics are the red grapefruit, olives and garlic.
When the bad cold is already plaguing you - stay relaxed and have plenty of warm liquids. Chicken soup and herbal tea can do miracles.
If your nose gets stuffed, try making some sea salt dissolved in warm water.
Use this solution as nose drops (turn your head back and get the drop in with pippette).
Lot more can be said, but I already wrote 1 or 2 hubs about it. Have a look around my profile.