Improve Your Rating by 400 Points

While this statement is aimed at chess players rated at about 1400 (USCF), the idea can be used by most chess players to improve their rating. Once again, I want to beat my drum about studying chess puzzles to improve your chess strength. Why?

As Michael de la Maza of www.Chesscafe.com states in his article "400 points in 400 days" (Part 1  Part 2), and his observation is backup by GM Jonathan Levitt and GM Nigel Davies,

"Chess knowledge is not the same as chess ability...and a player's chess ability is limited first and foremost by a lack of tactical ability."

And how does Michael recommend that you improve your chess ability?  Doing Chess puzzles and in his articles he recommends a study plan that he developed.