Probably the two most important rules about trading are, create a set of rules and then follow those rules, this may seem like common sense but you will be surprised by the amount of traders that have no clear strategy and without that how is it possible to evaluate their performance? And then there are those that do have a system but then when confronted with the realities of trading they refuse to follow their strategy and instead of cutting their losses they keep holding hoping the price goes in the other direction, and by doing that they damage their capital to the point that not even the best trader in the world could recover all the money they have lost.