An active day trader myself (sort of), I often think about common mistakes people make in trading. And it seems that I have traced back most if not all such mistakes to their root cause. In a nutshell, it all comes down to being unable to back out if something goes wrong. For example, you buy a few bitcoins at a December high and expect the price to continue rising, which is kind of obvious. Instead, the price starts crashing down and you find yourself in a situation that you didn't envisage or consider beforehand. So your best option would be to bring things back where they were as fast as possible even if it means some loss.

It is not so much about placing dumb stop-loss orders or other trading techniques aimed at minimizing losses as about your mental disposition or general attitude to immediately get out of what can be loosely called a decision limbo when you basically don't know what to do. In other words, search for the exit where the entrance is and do that fast.