The how is more important than the what. It really doesn’t matter what you study, the important thing is to use this as a training ground for thinking rather than trying to assimilate a mind-numbing amount of information. In these days of a zillion different chess products this message seems to be quite lost, and indeed most people seem to want books that tell them what to do. The reality is that you’ve got to move the pieces around the board and play with the position. Who does that? Amateurs don’t, GMs do.
Chess is not a game that can be learned from a book any more than tennis or golf. It may look rather academic and there are some scientific elements to it. But the truth is that wiles and playfulness count for far more than “knowing the book.” Interestingly my grandmaster colleagues tend to be quick witted, jovial and street wise rather than serious and lofty intellectuals. And most of us will recommend keeping a clear head both before and during a tournament rather than hitting the books. So why do amateurs believe it is otherwise? One reason may be that people have linked hard work to success and are convinced that the former is a prerequisite of the latter. In many fields this may be true, but the evidence indicates otherwise in chess. Most GMs have just played lots of chess and analysed their games because it was fun! I have read a few books from cover to cover, but many of my colleagues have not.
[…]I should point out that today’s chess industry does have a vested interest in persuading you that you need to be serious. They like to present it as something intellectual to keep selling books, it wouldn’t do at all if you were to go to a tournament and spend your time in the bar or analysis room. But this is where you’ll often find the titled players, moving the pieces around the board or just relaxing.
—Nigel Davies, from a ChessCafe column