Bulls Make Money, Bears Make Money, But Pigs Make Nothing

Traders can be that way, which is probably why this low-key philosophy stuck in my head. This brings to mind a couple of thoughts about buying stock. The first is that if you really like a stock and have done the necessary work to support your conclusion, then don’t let one-eighth of a point keep you out of the trade. Often investors will put an order in just under the offer, hoping to get a better price, and wind up missing the trade
because the stock did not drop that extra one-eighth. Or worse,

it really is a stock they want to own, and they end up buying it at a higher price. Unless you are day-trading the issue, if one-eighth or one quarter is going to make a difference, then maybe you ought to reevaluate the risk/reward parameters of the trade.

The second thought is when to take profits. Consider taking partial profits. Our money managers reduce a position by a third when they are up 30 percent and take another third off when they are up 50 percent. This strategy allows you to take some money off the table. It accommodates reducing risk while allowing the position to run. In addition, reducing the position as it grows helps to keep one stock from becoming too large a percentage of the portfolio.

To be successful, it is imperative to let profits run, but be smart as well and protect some of those profits

Source Tom Dorsey's Trading Tips - A Playbook for Stock Market Success Page no 152