[Warning: this one is a big longer and... maybe ranty. There's a TL;DR at the bottom.]
How do you pace your novel? How do you differentiate your scenes? Do you pay attention to high points and low points? Can you imagine drawing your novel out in a graph line, or some media visualizer? Do you think your book would make a good song? Does it have a beat? Are there notes and chords?
Music writing and storytelling are in many ways, the same. Both can evoke strong emotions, thoughtfulness and provoke socialisation. Music and books create shared experiences, which makes people come together. These can be real ones or false ones, I would argue that the difference is negligible. When someone writes a non-fiction account of a person dead two thousand years, it is almost entirely fiction. Events can be derived but the exact experiences are lost. We have a story that someone told about the incident, and anything could have really happened.
Music can have an advantage over writing in that when you are composing your story, you only need to (in the case of instrumental music) find the chord that inspires the emotion you feel inside you. You are using a limited set of notes that can exist on a certain instrument or instruments. You find the right ones, and string them together in sequence that responds to you -- therefore hopefully other people as well. The other advantage that music has is that people are all animals and we respond to many sounds in the same way, regardless of personal taste in music. The worldwide spread of dance music is a testament to this. It is cross-cultural and focused primarily on beats, which apparently evoke a very positive response in many, if not most humans. And while music is great at evoking fundamental emotions, to really cut to the core, you need language. The evolved version of music.
Okay. Brief aside. Skip to the bold if you don't want to hear a language rant. Language is not just a way to communicate, but a way to define a worldview. A classic example of this is that much of the world, we view time as forward-moving. Your future is ahead of you; you are moving into it. And your past is behind you. But for the Tuva people of Siberia the past is ahead of them, and the future behind them. Because you know your past, and you can see what's ahead of you. But you don't know your future, and you can't see behind you. Makes sense, doesn't it?
A different language carries all sorts of extra cargo. I'm not telling you this because I think you need to worry about translating your book while you're writing it -- worry about that after it's published and selling in your native tongue. But I am saying that you should identify your language's inherent norms, and see if they match the society you have crafted. Things that evoke automatic responses are often cultural artifacts -- anecdotes and similes that rely on shared cultural experiences. Like any reference to football in the US vs nearly anywhere else in the world.
So how do I make a song out of my book?
It's all about know what your notes are. For writing, it's your scenes. And the language you use to describe them. But broadly it is more important to focus on scenes. What emotions are you evoking? What scenes draw out in a response in every person? What, regardless of culture, does everyone share? If you want to make someone hungry, write about delicious food. If you want to make them sad, kill a friend. If you want to bring them up, give them success. Paint broad strokes; make chords. Using these basic shared experiences, like a primal beat on a dance jam, you can set your reader up for your message, and the emotional content you want to convey in more specific terms.
Besides having a vast array of emotions, you also need to have flat proper pacing. Again, the length of scenes and the intensity of the action should be viewed in the same way as movement of a song. Are they uptempo scenes or slow? Rising or falling action? If you just want a simple emotional punch, a single note can do the work of an entire book. For an expert example of what I'm talking about, read Hocus Pocus by Kurt Vonnegut. It is a book that it is "written" by a man living in an attic writing on every scrap of paper he can find, of any size. Sometimes that is only large enough for one word. And that one word, properly set up, can be the most powerful note in the whole tale. You could make a song out of Hocus Pocus.
This might have gone too deep, but the TL;DR is that you should read through your story, and draw it out like a visualized song. Is it all the same? Is it all up and then straight down? Just highs and lows or is there a flow, a cadence within your rising tension? Think of a great song you just love, one that just hits you and you can't forget. See if you can write your novel like a song. Or, for the bigger nerd, could you Audiosurf your book?