The question about learning a foreign language is rather difficult. To understand this psychological activity you must know some information about process in your brains while you are working. We must know about psychology of peoples mind and know about perceptual psychology too. The peoples abilities are different: one can study easily, another with great difficulties. But in spite of different abilities you can learn a language effectively if you have great interest in it. And, it is the main "secret" which you can use for effective learning of a foreign language.
