|Image: Jean-Remy Duboc|
Music Defines Person:
You've already picked out what music suits your character but neglect to put any of this into the story. While your character isn't going to be running around with theme music, a strategically placed song reference can help fill in blanks. It is especially helpful for characters with limited time in your books.
Don't believe me? Fine. A huge, menacing biker with a ripped leather vest stomps into the roadhouse. He gnashes his teeth, has ham fists, cliche... yada yada. And, when he finally leaves for the night, goes home and listens to the Carpenters in the dark. Did the "and" part give you a different perspective?
Music Defines Place:
Music can help tell you what kind of place your character just came into. Describe a regular diner with the red booths, smell of grease, swivel stools at the counter, etc. "Moonlight Sonata" plays over the sound system. Or, as much as this pains me "Milkshake" by Kelis. Try a place your characters go and put various types of music into it. Which one would fit and why? What does the place turn into with the wrong song?
Music can also help define an overall theme but I find it is a trickier line to walk, especially if your theme isn't music related at all.
Have you ever tried incorporating songs? Have you ever read a book with too many song references?