How does a new KDP writer supposed to market a book?

Because you cannot persuade readers to buy any book in which sentences do not make sense. This shouldn't be “does.” If you don't see the problem, that is a big problem.

Or

You cannot effectively promote books

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How does a new KDP writer supposed to market a book?

C) Persuade book reviewers on BookTok or Substack or someplace to recommend your book. If your book is unreadably terrible, this is probably impossible.

Or

Is it ok if I wear a bonnet as a person with straight hair? I used to have curly hair, but later on in life I got it treated, I’m not black, but my hair keeps getting frizzy every morning so I am considering it. Is it cultural appropriation?

B) that are filled to the brim with typos or errors.

Are you planning to proofread your book to avoid sentences such as

C) that are unreadably terrible in any other way.

Why won't biden give a last minute deferred action TO ALL undocumented immigrants so Trump can't deport them? Obama issued DACA, why can't Biden issue something similar that protects ALL undocumented immigrants from deportation?

If your book is well presented, well written, and basically free of typos, then

A) that are not actually books.

E) Take a solid year to learn how to use Amazon or Facebook ads and be prepared to lose quite a bit of money as you figure it out.

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A) Build a following on social media, a following of people who will buy your books. Good luck with that. There is very little evidence that social media can translate to sales.

B) Build a newsletter mailing list of people who will buy your book because they trust you to write books they want to read. This is slow, but ideal.

D) Pay promotion services like Written Word Media to promote your book. Legitimate services will not accept your book for promotion if the presentation is crappy or the book is badly written.

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D) that are presented with bad covers, bad descriptions, or ludicrously bad interior formatting.