After 28 years as a financial services coach probably the single biggest dilemma I have seen facing investors is when do I sell? How do I know if I should sell this stock? The old expression holds true: it's easy to buy, but really hard to sell.

Selling a stock is sometimes the equivalent of parting with a loved one. What if I just hold on, it might go a bit higher; or, the stock is down, you are disappointed and even angry. That discussion ranges from "I should have known better" to " you've disappointed me so much". A sociologist client of mine once told me that scolding a down stock is like addressing a juvenile delinquent. Same painful language.

So what do we do? Many professional portfolio managers will not buy a stock until they have determined in their minds a strict price target for selling it. Seems simple enough, but the art of investing is sticking to it.Emotions do enter the picture.

By sticking to it I mean that as the stock approaches your price target; it is time to have a frank conversation with your broker/advisor. You have to pretend you do not own it. Would I be a buyer here at this new higher price if I didn't own a share? Have the underlying fundamentals of the company (stock) or the industry in which it competes changed at all? Is the growth rate intact, or accelerating? Has the senior management given any indication that their publicly stated goals for revenues and earnings changed at all?

These are the hard questions that must be honestly asked, and more importantly, honestly answered. What you'll learn is that it's okay to keep the stock and raise your price target to higher levels. If the answers to the questions are lukewarm, then sell...and do not look back.

I had a British portfolio manager client that managed a multi-billion dollar US stock growth fund who raised his price target on Cisco Systems 33 times before he ever sold one share. The key to his success was to re-validate the reasons and the fundamentals of his stock over and over again. It is a refreshing process as you eliminate all your emotions from a stock story and as Joe Friday would say " just the facts, please".

The opposite action is also imperative if you wish to succeed as an investor. What is my downside protection price? If you buy a stock at $20, and it is now trading at $17, re-ask all the same questions all over again. Is it just a sloppy market? Are the fundamentals intact? Is senior management backing away from revenue and earnings projections? Has the growth rate begun to slow down? Would I be a buyer here if I did not own any shares? You get the idea.

Amazing things happen to the overall performance of a portfolio when strict price targets are established, both for the upside and the downside. Your losses are minimized and your profits are maximized