It is not the quality of your best moves that wins you games; it is the quality of your worst moves. The quickest way to improve your chess skills is to raise the bar. The Spanish grandmaster and coach Jesus de la Villa has proven with his best- seller 100 Endgames You Must Know that he understands exactly what a chess student needs. Building on his experience as a writer and as a coach for juniors, he has carefully selected the 50 Mistakes every player should be aware of - so the mistake can be avoided. De la Villa loves this quote from the American First