The short version: most small businesses feed AI a topic and a tone word like “friendly” and wonder why the output reads like every other LinkedIn post published this week. Build a proper brand voice document first, one with your real sentences, your real objections, and your real rules, and the output changes completely. It takes a weekend to build and it will save you hours every single week after that.
Why your AI writing sounds like everyone else’s
I did this to myself in early 2024. I asked ChatGPT to write a LinkedIn post announcing a workshop, told it to be “warm but professional,” and got back three paragraphs that could have come from any consultant in any country selling any service. Full sentences. No punch. No opinion. A client I was ghostwriting for at the time read the draft and said, quite fairly, “this doesn’t sound like you, it sounds like a press release.”
She was right. The problem wasn’t the tool. The problem was that I’d given it nothing to work with except a tone word. Tone words are useless to a large language model because every business owner on the planet types the same three: friendly, professional, approachable. The model has nothing specific to grab onto, so it defaults to the average of everything it’s read, which is corporate and forgettable.
What a brand voice document is (and isn’t)
It isn’t a style guide with a logo and a Pantone colour code. That’s for designers. A brand voice document for AI writing is a working file, usually four to six pages, that gives the model real examples of how you talk, what you refuse to say, and what you always say instead. Think of it less as branding and more as a transcript of you on a good day.
I compare this a lot to how Disney trains every cast member on how the brand talks before they ever touch a customer. Nobody hands a new Disney employee the word “magical” and leaves them to guess what that means in a sentence. There’s a whole internal language for it. You can see how deliberate that consistency is if you look at the way Disney built theirs into every touchpoint in this breakdown of the Disney marketing strategy. Small businesses need a scrappier version of the same idea, just one document, not a training programme.
The seven things mine contains
- Ten real sentences I’ve written pulled straight from old newsletters, not made-up examples. AI learns pattern from real text far better than from a description of a pattern.
- A banned words list, mostly corporate filler like “use,” “utilise,” “in today’s fast-paced world.”
- Three things I never do: never open with a question, never use three exclamation marks in one post, never end on a soft “let me know your thoughts!”
- My actual opinions on my topic, the ones I repeat often, so the AI stops being neutral and starts taking a side.
- Sentence length rules. Mine skews short. One-line paragraphs are allowed. A twelve-word sentence beats a thirty-word one nine times out of ten in my case.
- A “how I’d never phrase this” section, three sentences a generic AI would write, next to how I’d rewrite them. This contrast trains the model faster than any instruction does.
- Context on my business: what I sell, who buys it, what objection comes up most, so the AI stops guessing and starts writing to a real reader.
How I built it: the weekend that fixed everything
I pulled forty of my own blog posts and newsletters, roughly 40,000 words, and dropped chunks of them into a document alongside notes on what worked. Then I asked myself the boring but useful question every business owner skips: what do I say in almost every piece I write, without noticing I say it? For me it was one-line punches after a longer sentence, blunt opinions stated early rather than hedged, and specific numbers instead of “a lot” or “many.” I wrote those patterns down as rules, not just habits. If you want a head start, I have put the structure I use into a free brand voice prompt template you can copy and fill in.
Before this document existed, editing an AI first draft took me about 45 minutes because I was rewriting nearly every sentence. After I built the document and started feeding it into every prompt, that dropped to roughly 8 minutes per post, mostly fact-checking and adding a personal example the AI couldn’t invent. That’s the actual return on a weekend of work: five to six hours saved a week, every week, for a job I do constantly anyway.
If your business runs on regular content the way a subscription or membership brand does, this compounds fast. Headspace built its entire tone around calm, plain language repeated so consistently that people can spot a Headspace sentence out of context, and you can see how that discipline shows up across every channel in this look at the Headspace marketing strategy. Consistency like that isn’t luck. It’s a document somewhere that everyone writing for the brand is working from.
The uncomfortable bit most people skip past
Here’s what nobody selling AI tools wants to say out loud: a brand voice document doesn’t fix lazy AI use, it just makes the laziness less obvious. Plenty of small business owners are now publishing AI content wholesale, first draft, no edit, no personal example added, and the voice document just makes that unedited draft sound slightly less generic rather than making it good. I’ve read newsletters from consultants I respect that are clearly one prompt and zero human touch. The document narrows the gap between AI-average and human-specific, it doesn’t close it.
The other truth is that AI, even with a strong voice document behind it, is still better than most freelance ghostwriters you’d hire for £150 a post, and it’s still worse than you on a day when you have something to say. Anyone telling you AI writing is either useless or a total replacement for your own voice is selling you something. It’s neither. It’s a fast first draft from someone who’s read your last forty pieces of work and none of your new thinking.
Where this breaks down
It won’t help you if your writing has no consistent pattern to begin with, which is common with businesses that have never written in their own voice before, only ever hired freelancers to write “on brand” copy from a brief. In that case you’re not building a voice document, you’re inventing a voice from scratch, and that’s a longer job, closer to what GoDaddy did when it moved its entire brand away from the cheeky, laddish tone of its early Super Bowl ads toward something more founder-focused and small-business-friendly, a shift you can trace through the GoDaddy marketing strategy. That kind of repositioning takes months, not a weekend.
It also won’t fix content that has no argument in it. Richard Thaler’s whole career was built on noticing that people don’t act the way models predict, and that small nudges based on real behaviour beat big theoretical frameworks every time, a point worth sitting with if you look at the business lessons from Richard Thaler. The same applies here. A voice document nudges the output toward you. It cannot invent an opinion you don’t have. If your prompt has no point of view in it, no voice document on earth will make the output interesting.
If you’d rather have someone build it with you
You can do this alone in a weekend if you’ve got forty pieces of your own writing sitting somewhere. If you don’t, or you’d rather someone pull the patterns out for you and set up the prompts across your tools, that’s a fairly quick, contained piece of work, and it’s exactly the kind of thing I do with clients through AI implementation coaching, usually alongside the wider content and workflow setup rather than as a one-off document. Worth asking about if you’re already paying someone to write for you and getting inconsistent results.
One last practical note: keep the document itself boring and specific rather than clever. Coco Chanel didn’t build one of the most recognisable brand voices in history with a mood board, she built it by repeating the same handful of blunt rules for decades, “simplicity is the keynote of all true elegance” said a hundred different ways across forty years, which is worth remembering if you want the shorthand version in these business lessons from Coco Chanel. Repetition of a few real rules beats a long, vague document every time.
Frequently asked questions
How long should a brand voice document be for AI writing?
Four to six pages is enough. Longer than that and most AI tools lose the thread of what matters most. Real example sentences do more work than long descriptions, so favour those over paragraphs of explanation.
Can I use ChatGPT to help write my own brand voice document?
Yes, but feed it your own old writing first and ask it to identify patterns, rather than asking it to invent a voice from a description. It’s far better at spotting patterns in your text than at guessing tone from an adjective.
Does a brand voice document work for video scripts and emails too?
Yes, the same document works across formats because it’s built on sentence-level habits, not on a single type of content. You’ll still need format-specific instructions, like shorter sentences for video, layered on top.
How often should I update the document?
Every few months, or whenever you notice the AI output starting to drift back toward generic. Add new real examples from your best recent writing and drop anything that no longer sounds like you.
Related reading: I Write Client Proposals With AI in 20 Minutes. Here’s the Bit Nobody Tells You and Why ChatGPT Ignores Your Small Business (And What Gets You Mentioned Instead).
