Each person's path to success may be unique, but there are many commonalities among the world's most successful people. 

For his book, "The 8 Traits Successful People Have in Common," author Richard St. John conducted interviews with more than 500 highly successful people, from the likes of Bill Gates and Richard Branson to Martha Stewart and Ben Cohen, the cofounder of Ben and Jerry's ice cream.

St. John entered transcriptions of every interview into a database in order to analyze more than 300 possible success factors. He found they all shared eight traits, which he calls the "8 to be great" because "they're the foundation for success and greatness in any field."