There are several approaches to memorize the German vocabulary. Someone advised to study them only in the context of someone recommends to distribute words into groups united by a common concept and within the group divided into blocks. There are other techniques (for example, word cards).
I, in turn, offer the following method: in view of the peculiarities of the German word formation (compounding) to teach not only the particular word, but also simultaneously with words derived from the original word by adding bases. This word "pulling" for a large truck other words, and your vocabulary increases several times. In other words, it is necessary not only to remember that the word die Bahn means "road", but learn and a lot of other derivative words: Strassenbahn, Eisenbahn, Radrennbahn and so on.
I collected words I combined in this Android application to search and index.