Biggest Mistakes that Entrepreneurs Make?

I need your suggestions. I'm working on a presentation titled "The Seven Biggest Mistakes Entrepreneurs Make" and so far I have only my top four.

Most of them I've made myself and I'm sure I can complete the list, but it would help to have some consensus from other entrepreneurs and their consultants/advisors.

From your experience what are the most common mistakes and what do you recommend to avoid or fix them? I would appreciate your input.

For some hints, but here’s my list to date:

1. Neglecting strategic vision, too entrepreneurial/opportunistic/reactive/intuitive
2. Not knowing and managing your numbers
3. Neglecting key strategic relationships
4. Letting the product sell itself, poor marketing and sales support

Others have already offered:

5. Hiring too fast, firing too slow
6. Poor communication with employees
7. Under capitalisation
8. Poor research and planning
9. Neglecting to manage cash
10. Too corporate, no personality

And more…. So now it's your turn.

Thanks.