Alice Munro was wary of handing out rules. She'd won a Nobel Prize for the short story, but when asked what a young writer should do, she mostly warned against easy answers. What she offered instead was closer to a description of how she survived her own process.

The Direct Answer
Write through the wrong tracks, and know when a story stops being yours.
Munro distrusted universal rules for writers, per her 1994 Paris Review interview.

Why She Wouldn't Give Rules

Asked in her 1994 Paris Review interview to advise young writers, Munro refused the usual scripts. Tell someone to read, she said, and they might read so much they freeze. Tell them to ignore everything and just write, and you may get a mountain of nothing. Every young writer was too different for a single instruction to fit.

It's not possible to advise a young writer because every young writer is so different.

Alice Munro, The Paris Review, 1994

What She Practiced Instead

Her real advice sits in how she worked. She expected to get onto the wrong track and to haul herself back, so she kept moving through drafts that embarrassed her rather than waiting for a clean one. She believed the way through a story ran straight through its mistakes, and that playing with a flawed manuscript was how you found the right version of it.

She was just as firm about stopping. A story had to reach a point where it wasn't hers to keep fiddling with, the way a grown child stops being yours to manage. Revise hard, then let it go before you revise the life out of it.

For the routine that carried all of this, see the full Alice Munro writing routine.

What You Can Steal