Never let a black cat cross your path, never break a mirror and whatever you do don't use a broom at night, you'll sweep all the luck out of your house (i guess it doesn't apply to day time..lol)
The Word Book of Encyclopedia stated: "Most people have fears that make them feel insecure. Superstitions helps overcome such fear by providing security. They assure people that they will get what they want and avoid trouble".
However the bible shows that time and unforeseen events befall us all whether we are superstitions or not. (Eccl. 9:11)