Every writer knows the term "first draft" and our reaction is varied. [Cue eye roll.]
Sometimes it comes with a heavy sigh.
Other times a smirk.
Other times a laugh.
The first draft isn't a necessary evil. Operative word 'evil.'
It's the point when we get our asses into a chair and begin to write. What spills out? Honestly, that depends on how much I've ruminated on the elements of my story. The stronger the character voices resonate, the more I'm in touch with their arcs, their issues, and where to start.
So the first draft isn't truly the first time I'm in touch with my WIP. If I play my cards right in order to write, I thinking, crafting, deducing the story elements long before my posterior end connects with the seat.
What to do before the first draft gets processed? Just be....(Zen 101) in touch with the characters. Which is great for those like me who craft a character driven story. Give the gift of time to the people you create by allowing a lifeline.
What do you get? They'll eagerly tell you their side of what they did and why. Patience can't be overstated. That best idea ever may need some time to percolate and what comes out is better than a Starbucks' Caramel Macchiato.
At least it works that way for me. So during NaNoWriMo when writing like your fingertips are on fire isn't working. Take a break. Go for a walk. And be. What you're doing is opening a door and if you relax and listen, soon those voices will break through the chatter, little by little overtaking the white noise buzz until it's all you can hear.
When the din is too much to take, it's time to sit down and begin that first draft.
Works that way for me. Good luck
in your journey.