most of the traders do same mistake again and again , they should come out from losses , otherwise no way to bring profit with consistency.
i think after having a good knowledge loss will happen of course , no way to deny . so we traders should take losses as an easy things.
emotion is a thing that traders will not control at all completely, because it's common human nature. so we should take it as an easy thing.
I think trading without proper knowledge, impulse trading, and emotions are the common mistakes a trader made.
knowledge is important , no way to deny but any kind of knowledge can be useless if there is no regular level of practice.