Engage your heartbrain, that is to say your whole, deepest self. By tapping into your heartbrain, you'll be writing up a storm, hence the technique is called stormwriting. This is a results-driven tool that should be used time and again.
Stormwriting is essentially a heartbrainstorm, a process by which you open your heartbrain and provoke it to not merely dump stuff out, but generate new questions and ideas that lead you to more good stuff: The stuff that becomes building blocks for your book. How do you provoke it?
No matter what you come up with, no matter how much it's not what you're expecting, no matter how off the wall or even dumb, you don't resist it or ignore it. You run with it. You say, "Yes, and-" ... and the room begins to fill with the mutant ions from the forgotten medical waste facility next door!
You accept it and you go with it, and you build on it and you play off of it. The whole piece might stumble and change direction anytime, but you'll be in harmony with it.
This technique is outlined in Elizabeth Sims' book