If you've already gotten the flu then there's really not much you can do to speed up the recovery of the flu.
But you should stay hydrated, avoid caffeine, get plenty of rest and take some fever reducing medication and once again get plenty of rest and within a week or 10 days the flu should be gone.
Before you get the flu though you should get prescribed Tamiflu though which when taken 48 hours before the onset of the flu then you'll recover quicker or may not even come down with the flu at all.