One of hte most common problems I have encountered with budding entrepeneurs is their inability to be flexible in their thinking. That is it is a 'their way or the highway' approach to the development of a business concept. Unfortunately investors don't really warm to this sort of approach.
Constructive observation should be filtered into the thinking of every business person. In developing my own Firm I have learned so much from making mistakes, backing the wrong people and ideas and making numerous other mistakes. Although the strategy has always ben there, the ability to execute has been held back at times by simple mistakes.
Today I counsel with as many people whom I respect in business as I can. I have learned to think independently about all issues, and to be flexible in business planning.