Heather Sangster

I'm an accomplished veteran publishing professional who has been in long-time service (since 1988) to 28 trade publishers and imprints (including three of the Big Five: Penguin Random House, HarperCollins, and Simon & Schuster), prominent authors, businesses, and emerging talent across the globe. I've been Margaret Atwood's primary copy editor and proofreader for 31 years, most recently for our 22nd title together: her 2025 New York Times best-selling memoir, Book of Lives. Contributing my editorial services to 1100+ titles so far, I'm grateful to play a part in my clients' achievements: 70 bestsellers, 154 awards, and counting. I've honed my technical expertise in multiple industries (legal, educational, academic, and trade publishing; advertising), mediums (newspapers, magazines, books), genres, and in-house and freelance roles. I'm also co-founder of Strong Finish Book Editing (formerly Strong Finish Editorial Design). We've been providing decades-long ongoing editorial support to publishers and businesses while helping emerging writers produce audience-ready professional manuscripts since 2006. Knowing what works is key. I combine classic principles, contemporary sensibilities, insider expertise, and just the right touch for a signature service with measurably superior results.

Copy Editing: What It Changes, What a Style Sheet Is, and What It Costs

Co-founder of Strong Finish Book Editing. Editing since 1988, for 28 trade publishers and imprints, including three of the Big Five. Margaret Atwood’s primary copy editor and proofreader for 31 years, across 22 titles. Copy editing is the pass that makes a manuscript correct and consistent. It fixes grammar, punctuation, spelling, and usage, and it

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Line Editing: What It Is, What It Costs, and How It Differs from Copy Editing

Co-founder of Strong Finish Book Editing. Editing since 1988, for 28 trade publishers and imprints, including three of the Big Five. Margaret Atwood’s primary copy editor and proofreader for 31 years, across 22 titles. Line editing is the pass that fixes how your book sounds. It works on rhythm, word choice, clarity, and tone, one

Line Editing: What It Is, What It Costs, and How It Differs from Copy Editing Read More »

Manuscript Evaluation: What You Get, What It Costs, and When It Saves You Money

Co-founder of Strong Finish Book Editing. Editing since 1988, for 28 trade publishers and imprints, including three of the Big Five. Margaret Atwood’s primary copy editor and proofreader for 31 years, across 22 titles. A manuscript evaluation is a full read of your book, followed by a written report. You get an honest account of

Manuscript Evaluation: What You Get, What It Costs, and When It Saves You Money Read More »

Developmental Editing: What It Is, What It Costs, and When Your Manuscript Needs It

Co-founder of Strong Finish Book Editing. Editing since 1988, for 28 trade publishers and imprints, including three of the Big Five. Margaret Atwood’s primary copy editor and proofreader for 31 years, across 22 titles. Developmental editing fixes what your book is, not how it reads. It works on structure, argument, plot, pacing, and character, and

Developmental Editing: What It Is, What It Costs, and When Your Manuscript Needs It Read More »

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