The old method.

The study of openings, no doubt an important part of Chess preparation, is not always addressed in an appropriate manner. Many players, even experienced ones, do so by memorizing several fashionable lines. This approach has two serious drawbacks: as time goes by, their memory won't be able to recall all the lines; furthermore, if their opponent takes them out of their preparation, they are left without any useful reference to orientate themselves correctly in the new arising position.