How can you avoid the pitfalls that destroy most entrepreneurs? Rob Kelly, a San Francisco-based Internet veteran who has started, sold, bought and, by his own admission, even bankrupted a business, says there are five major mistakes entrepreneurs of failed businesses make. If you avoid these mistakes, he says, your chances of creating a winning business go way up.

1. Failed entrepreneurs believe that "if you build it, they will come": Webvan is perhaps the most compelling example of a business that assumed tons of customers would flock to its service.