I don't really have an exit strategy put in place for any of my holdings. The intention is to buy and never sell. Obviously this is very easy in theory but in the real world you're going to be cutting ties with plenty of purchases you make. You'll never be right 100% of the time.
The best exit strategy is, interestingly enough, just knowing why you bought. Developing an investment thesis as to why you purchased a company makes it very easy to just cut ties with that company and move on if things change.
A prime example of this would be my position in Enghouse. I purchased the company because of managements history of being able to execute in terms of acquisitions to fuel growth. The company fumbled the ball in terms of acquisitions and integrating them for about a year and I just cut ties. I knew why I bought, which made it very easy to know when to sell.