Delia Sherman has some lovely (and very timely) advice to a young relative on surviving the first draft.
Whatever you do (and I’m sure there are other things I’ve never tried or thought of), get that shitty first draft done. You can’t fix something that doesn’t exist. You can’t rewrite a faulty text that’s still mostly in your head. You can’t experience the thrill of making a recalcitrant scene or section work by changing a paragraph, cutting a sentence, adding the perfect line of dialogue if you haven’t written the clunky version first. Do whatever it takes.