If you're about to get on a plane, what should you do--and avoid doing--to assure a safe flight? What does it mean if you see an ambulance zoom by? And is a black cat always unlucky? Though we may say we don't believe in superstitions, they have an unmistakable power...and to be on the safe side, most of us secretly knock wood, don't walk under ladders, and avoid opening that umbrella indoors. Broken up into categories such as animals, astrology,...