This is what I do:
1) At first I play a song without explaining any vocabulary or grammar constructions. I just let students listen to it and then I ask them some general questions (What is the song about? What happened? What is going to happen) or I ask them to tell me any words/phrases/sentences which they remember/were able to understand.
Or... I mention the topic of a song and ask the students to tell me the words/phrases that may be used in this context. We make up a list of such words and while listening the students have to tick off the units used in a song.
2) Then I introduce the words that may be unknown for them. To practice these words I prapare a "fill-in" exercise.
3) After that I ask some questions that may provoke discussion (Do you agree...? What would you do if...?)
I hope it will help