What would be the most important advice you could give to aspiring writers?

Holly Black gave this advice one time, and it has stuck with me:

“Don’t write for your writer self. Write for your reader self.”

Write the story you want to read. In that first draft, throw it all on the page. Don’t try to restrict yourself by writing a perfect story in the first draft. Instead, as Anne Lamott has taught me in her book BIRD BY BIRD, let your writing breathe and move and weep and leave a trail of clutter on the page. Your picky, perfectionist writer self can edit things in your second and third drafts.