get a flu shot, use common sense precautions. Wash your hands often, have a small bottle of Purell handy. If you use the public restrooms, again wash your hands really well. Get plenty of rest on your cruise, don't over do it. Drink plenty of water inbetween the frou-frou cocktails. Also up your daily intake of Vitamin C ( drink an extra glass of OJ) great germ fighter.