No Exit Strategy
In a perfect world, the business you build is a legacy for your children. You set up that newspaper empire (assuming you're in the newspaper business) and then pass the company to your eldest child. After that, you get to spend your retirement napping with the grandkids and playing with your childhood sled.
But it doesn't always work out that way. In the absence of a set plan, family members and employees may fight for control of the company. Or even worse, they decide they want nothing to do with it. Calling in the lawyers to document your succession intentions five to 10 years before retiring is an absolute must. For extra security, prepare to negotiate a management buyout or to sell off the business if a dynasty isn't in the cards.