1.)Listen to a song.
2.)Draw how the music goes. You can draw instruments how the tone feels (smooth/rough).
3.)Draw as you listen and don't spend more time on the picture/design/comic then the length of the song.
4.)Title and sign.
Example:
Song: Girl (artist=Beck)
http://youtube.com/watch?v=IK7GsFF8KR0

Song: Sheep Go to Heaven (artist=Cake)
http://youtube.com/watch?v=e0mx5ERj1eI

This is only one way to do it, you could use any song, and any interpretation of that song. (You can make one overlying picture, and it doesn't have to be scattered like this. It could even be coherent!)
These aren't great examples in my opinion. I can't use MS PAINT for improvisation very well.
Please contribute any suggestions or anything.