Entrepreneurs are necessarily optimistic. You need to be, it allows you to see the possibilities around you and act on them.

However, the downside is that your emotional attachment can blind you to problems that are otherwise obvious to someone who is not as personally invested in the project.

This is why smart entrepreneurs learn to wear six hats: six "Thinking Hats". Originally defined by psychologist Edward DeBono, the Six Thinking Hats are a structured creativity tool to…