You can’t cure colds and flu, so you must prevent. Charles B. Inlander, president of The People's Medical Society, offers these suggestions (WebMD Medical Reference):
Wash Your Hands
Most cold and flu viruses are spread by direct contact. Someone who has the flu sneezes on their hand, then touches the telephone, the keyboard, a kitchen glass. Germs can live for hours - in some cases weeks - only to be picked up by the next person who touches the same object. So wash your hands often. If no sink is available, rub your hands together very hard for a minute or so. That helps break up most of the cold germs.
Don't Cover Your Sneezes And Coughs With Your Hands
Because germs and viruses cling to your 
bare hands, muffling coughs and sneezes with your hands results in passing along your germs to others. When you feel a sneeze or cough coming, use a tissue, then throw it away immediately. If you don't have a tissue, turn your head away from people near you and cough into the air.
Drink Plenty Of Fluids
Water flushes your system, washing out the poisons as it rehydrates you. A typical, healthy adult needs eight 8-ounce glasses of fluids each day. How can you tell if you're getting enough liquid? If the color of your urine runs close to clear, you're getting enough. If it's deep yellow, you need more fluids.
