First, designate one person--keep the rest of the family away.
Be sure the sick person stays home and remains there until 24 hours after the fever lifts.
Set up one sick room. If more than one person is sick--they can be in the same room.
Have the sick people use one bathroom.
Get tissues, line a wastebasket with a bag that lifts out. Get an alcohol-based hand sanitizer. Put drinks in an ice cooler in the room to cut down on trips. You may want a humidifier to make it easier to breathe.
If the sick person leaves the room, he or she should wear a mask.
My sister and mother once--many moons ago--had the Hong Kong flu. I was the caregiver. My advice: Don't give them a bell to ring to summon you. Once they feel a little better, they can ring it.