You can help to keep the flu virus at bay by washing your hands often with hot water using antibacterial soap, the hotter you can stand the water on your hands the better.
The hot water along with the antibacterial soap will help to kill off the flu virus, be sure to get your flu shot as often as needed too.
When you need to be around someone who has the flu it's best to wear a breathing mask or if you have the flu virus yourself and need to be around others wear a breathing mask to help prevent the spread of your flu virus.
Also make sure to get plenty of Vitamin C and eat healthy and get plenty of rest to help keep your immune system built up.
You can try what you can to prevent the flu but there's no guarantee you won't get infected with the flu virus.