I've had my fair amount of mistakes from game to game, and one thing that may be seen as a set back, is not reviewing your mistakes, and learning from them. Chess can consist of trial and error, and you won't improve if you don't review the errors made. After you review the mistakes, you must learn what to do in order not to make them again, but most of the time it is easy to forget everything once you play again. It's like studying for a school exam, then forgetting everything the very next day, what should one do to not repeat the mistakes, and what should you do to remember how not to make those mistakes?