Kazuo Ishiguro doesn't hand out tidy slogans. His most useful advice is baked into how he actually drafts: fast, messy, and without stopping to fix a thing. It runs against the careful stylist most readers picture.

The Direct Answer
Draft free-hand and let the bad writing stay on the page. Sort it out later.
It's the method Ishiguro used on the 'Crash' draft of The Remains of the Day, described in his 2014 essay for The Guardian.

Let the Bad Sentences Stand

The instinct most writers fight is the urge to perfect the last sentence before daring to write the next one. Ishiguro's approach smothers that instinct. During his four-week Crash on The Remains of the Day, he wrote by hand and refused to slow down for quality.

Throughout the Crash, I wrote free-hand, not caring about the style or if something I wrote in the afternoon contradicted something I'd established in the story that morning.

Kazuo Ishiguro, The Guardian, 2014

Awful sentences, clumsy dialogue, scenes that led nowhere: he left them in and kept going. The logic is simple. A first draft exists to get the ideas out where you can actually see them. Judgement comes afterwards, once there's something on the page worth judging. The bet is that stopping to polish mid-flow is how promising ideas get talked out of existence before they've fully formed.

Draft a Version Nobody Else Can Read

There's a related habit he described in his 2008 Paris Review interview. Ishiguro drafts in longhand on a writing slope and keeps the handwriting deliberately rough, more or less illegible to anyone but himself. The messiness is a feature. A draft only you can read is a draft you won't be tempted to show off, which frees you to be bad on purpose. He caps a working day around five or six pages, then later numbers the sections and reorders them into something coherent. The shaping is a separate job from the writing, and he keeps it that way on purpose.

Trust Imagination Over Autobiography

Ishiguro has also pushed hard against the old workshop line to 'write what you know', calling it about the most useless advice he's heard and saying it nudges writers toward dull autobiography instead of firing the imagination. His own best-known books bear that out. They reach far outside his direct experience: an English butler, a compromised painter in postwar Japan, clones raised to donate their organs. The thread linking that to the messy drafting is the same. Get the raw material down first and worry about polish, and plausibility, second.

For the daily habits behind these drafts, the hours, the pages, the pen, read the full Kazuo Ishiguro writing routine.

What You Can Steal