Don't take vaccines or flu shots as they are not proven to work and are made of 100% toxic stuff.
Eat a lot of fresh fruits and vegetables; they are full of vitamins and minerals. Here is an interesting article about the 3 best winter herbs:
If you do get sick, stop eating solid food right away. Drink only freshly pressed vegetable and fruit juices (enemas help too) to beat the sickness in a flash.