Most of my books have them. I find one that encapsulates the mood of the book and then play it until I can sing every word by heart.
For GRIMSPACE, it was Song to Say Goodbye by Placebo. For WANDERLUST, it was Lost Cause by Beck. For BLUE DIABLO, the first Corine book, it was Me Muero by La 5ª Estación. I provide links so you can check the songs out if you’re unfamiliar with them.
Now here’s the song I listened to religiously while writing HELL FIRE. It’s sad, soulful, and a little heart-wrenching.