Think in terms of probabilities and not certainties

Trading is about having the ability to think in terms about probabilities and not certainties.  A typical scenario is when you entered into a short with a double top, it doesn't mean the formation is going to be a definite signal that the price is going down.  So, when the setup show signs of failure, it's time to get out and not holding to the original view.

Thus, the key to trading success is management.