Your best protection against contracting the flu is to get vaccinated each fall season. You should also follow good health habits and use antiviral medications. The flu and colds are generally spread from person to person when an infected individual coughs or sneezes.
In order to prevent the spread of germs cover your mouth and nose when you sneeze or cough. Get into the habit of regularly washing your hands with soap and water. After that, run your hands vigorously together and thoroughly scrub all surfaces. Take between 15-30 seconds to wash. If you do not have access to soap water, you can use alcohol based disposable hand wipes or gel sanitizers. These can be purchased from drugstores or supermarkets. Gel should be rubbed into the hands until dry (you don't need water). The alcohol in the gel will kill the germs that cause colds and flu.
You should also avoid touching your eyes or mouth. If you are sick, stay home rather than going to work and spreading germs. You should also avoid close contact with people who are sick. If you are sick, be considerate and limit your close contact with other people.