Vocabulary needs to be revised again and again. Well, what could be better than studying vocabulary by listening to your favourite songs?
Read the lyrics first and try to understand them. You don’t have to translate the lyrics word by word, just try to find out what the song is all about. (Note: ‘Rap’ might not be practical as those songs usually contain slang words that not even ‘ordinary’ English native speakers know.)
Pick some words or phrases from the song that you would like to learn. If necessary, look up their exact meaning in a dictionary. A dictionary might also be useful to find other interesting phrases with the word.
Now, to learn the vocabulary, all you have to do is listening to the song again and again (that shouldn’t be a problem if it’s one of your favourite songs).
Let the music turn you on.