All the very best traders and investors have a method that will give them an edge. Having an edge means the odds, or probabilities are in your favor each time a trade is initiated. The method implemented depends upon the individual traders philosophy. It can be technically based, fundamentally based, or a combination of both. It can be short-term or long-term. There are very successful traders with methods that are completely different. You simply can not win unless you have a method that puts the odds in your favor. This includes the stock market, or any other trading venue.
Discipline is an absolutely crucial element. All the great traders and investors know that without discipline, it does not matter how good your trading plan or method is. You need discipline to implement your trading plan. You can not be second-guessing your entry signal, exit signal, and money management rules. Basically, you must have the discipline to completely follow every part of your trading plan. This will also help keep emotions out of your trading.
Top traders and investors fully understand that sometimes a trade you put on, is not going to work out. They realize that some trades are going to result in a loss. The key is to keep all losses small. There are fantastic traders in the stock market and futures market, who only win about 50% of their trades. The key is their winning trades tend to result in substantial profits, while their losing trades result in only small losses. The best traders know they will win over the long run. Taking a small loss does not bother a great trader at all.