In your opinion what are some of the worst mistakes entrepreneurs can fall into?

One of the worst mistakes an entrepreneur can fall into is becoming complacent when you're successful and things are going well. It's easy to sit back and let things just go on autopilot and maybe not think in terms of the future, especially if you have a very successful business going on. I think you have to be careful not to have all your eggs in one basket. Not to have only one big customer because if that customer goes away, your business goes away. Not to be totally dependent on anyone vendor nor be dependent on any one or two employees so that if you lose them your business doesn't function. You have to diversify with product, customer and employees, so that you have a business that is ongoing and won't fall apart if just one of those things goes away.