What is your tolerance for pain? Consider the following scenario. You have 10% of your account balance on the line. For the past two days, prices have been going in the direction you had anticipated, but today, an announcement was made that caused a market move that caused all your profits to be wiped out in an hour. What will you do? See if prices will move back to where you are okay again? At times like these, it is useful to have a clearly defined trading plan with a specific exit strategy.
Trading is inherently uncertain. You never know exactly what will happen next. That's what makes the business exciting to some traders but nerve wracking to others. How you handle adverse events that make prices move against you depends on your personality. The best way to protect your capital is to use protective stops. When formulating your trading plan, you must decide how much pain you can tolerate. How much money can you lose before you have to exit the trade? You can set this exit point as a formal stop loss, you can use the automatic settings on your trading platform to set a stop, or you can use a mental stop (not recommended).
The problem with a formal stop loss procedure, whether it is a formal order or an automatic setting on your trading platform, is that a transitory change in price can 'stop you out.' if the placement of your stop loss does not adequately account for volatility. It's hard to know how far a stock may move and a temporary drop can ruin your trading plan when a protective stop is not set properly. Mental stops may be more useful, but you run the risk of not being able to exercise your mental stop (think heart attack, nervous breakdown, stroke, personal emergency, computer failure, etc.). You can decide how far a stock price must move against you before you will liquidate the position. When prices reach the exit point, you can decide whether the low price is transitory or represents a significant change in trend. You can then exit the trade.
This all sounds good in theory, but depending on your personality, you may not be able to carry out this strategy. If you have trouble controlling your emotions and you use a mental stop, for example, you may have trouble closing the trade when it reaches your exit point. Some people panic and out of fear don't close their position when their mental stop is reached. These people may need to impose the proper amount of discipline on their trading actions by using an electronic stop or a formal stop-loss order.
Minimizing trading losses is the hallmark of successful trading, but not all traders are equal when it comes to their ability to trade decisively under strain. If you want to trade profitably, you have to work around your personality. If you are cool headed, disciplined, and are willing to take the risk even under the most stressful conditions, you can use mental stops to protect your capital. But if you are easily shaken by choppy market action, you might want to use electronic, automatic stops to protect yourself. Whatever you do, however, minimize losses as much as possible. It's the only way to trade profitably in the long run.
I’m finding that formulating a trading plan inline with your personality is a process of refinements over time!