Many club players think that studying chess is all about cramming as much information in their brain as they can, especially regarding openings. Most textbooks support that notion by stressing the importance of always trying to find the objectively best move. As a result, amateur players are spending way too much time worrying about subtleties that are really only relevant for grandmasters.
Emanuel Lasker, the second and longest-reigning World Chess Champion (27 years!), understood that what a club player needs most of all is common sense: understanding a set of timeless principles. Amateurs shouldn't waste energy on rote learning but just strive for a good grasp of the basic essentials of attack and defence, tactics, positional play and endgame play.
Chess instruction and study needs to be efficient because of the limited amount of time that amateur players have available. Superfluous knowledge is often a pitfall. Lasker himself, for that matter, also studied chess considerably less than his contemporary rivals.
Gerard Welling and Steve Giddins have created a complete but compact manual based on Lasker's general approach to chess. It enables the average amateur player to adopt trustworthy openings, reach a sound middlegame and have a basic grasp of endgame technique. Welling and Giddins explain the principles with very carefully selected examples from players of varying levels, some of them from Lasker's own games.