Teaching AI your brand voice with a style sheet

Every time you open a fresh conversation with an AI assistant, it knows nothing about you. It doesn't know that you write in short sentences, that you never call members “customers,” or that you'd rather make a gentle joke than use an exclamation mark. So it falls back on a polite, generic register, and you spend twenty minutes editing that out of every draft.

For a membership site, the risk is bigger than wasted minutes. Members pay for a relationship with a particular voice, and welcome emails, lessons and renewal reminders should all sound like they came from the same place. A brand voice style sheet is a short, reusable document you give your AI tool so every draft starts closer to how you actually write.

What a voice style sheet contains

A voice style sheet is not a brand book with logos and colors. It's a page or two of plain instructions about words. The most useful ones cover:

• Who you're talking to. A few lines about your members: their experience level, what they worry about, what they already know.
• How you sound. Three or four traits, each with a short explanation of what it means in practice and what it doesn't mean. “Friendly, but not gushing” is more useful than “friendly.”
• Words you use and words you avoid. Your terms for members, content and levels, plus phrases that make you wince.
• Formatting habits. Sentence and paragraph length, whether you use headings and lists, how you sign off, whether you use contractions.
• Examples. Two or three short passages you wrote and are proud of, labeled as good examples, and one rewritten “not like this” version.

The examples do more work than any description. AI tools are good at imitation, and a real paragraph of yours teaches rhythm and word choice in a way adjectives can't. For the wider house rules that sit alongside it, such as spelling and formatting conventions, see creating a simple style guide for your membership content.

Let AI help you describe your own voice

Most people find it hard to describe how they write. This is where AI earns its keep: it's quite good at noticing patterns in text you give it. Delphine, who runs a watercolor painting club, gathered five pieces she liked best: two lesson introductions, a welcome email, a forum post and a short article. Then she asked for an analysis.

Below are five pieces of writing from my membership for [describe your members]. Analyze my voice. Describe it in 3 to 5 traits, and for each trait give a short example from my writing and explain what it would look like if taken too far. List words and phrases I use often, typical sentence and paragraph lengths, and anything I seem to avoid. Then draft a one-page voice style sheet an AI assistant could follow. Only describe what you can see in the samples; don't invent preferences. [paste your five samples]

Delphine's draft came back describing her as “encouraging, practical and lightly self-deprecating,” which felt right. It also said she “often uses exclamation marks for emphasis,” which she didn't like at all once she saw it written down. That's a useful outcome too: the analysis showed her a habit she wanted to drop, so she added it to the avoid list.

Edit the style sheet by hand

Treat the AI's version as a first draft. Read every line and ask whether you'd be happy for a new staff member or freelance writer to follow it. Tighten vague traits, add the words only you use, and remove anything that describes a quirk rather than a choice. Then add the “do and don't” pairs that matter most. Tom, who runs a cycling coaching program, added these:

• Do say “riders.” Don't say “athletes” or “users.”
• Do give one clear next step. Don't end with a list of five options.
• Do admit when a session will be hard. Don't promise that anything is “easy.”

Keep it short. Long sheets tend to get followed unevenly.

Turn it into a reusable prompt

Once the sheet is ready, wrap it in a standard opening you can reuse for any writing task:

You're helping me write content for my membership, [membership name]. Follow the voice style sheet below for everything you write in this conversation. If an instruction from me later conflicts with the style sheet, point it out rather than silently choosing one. [paste voice style sheet]. First task: [describe the piece, its audience and its length].

You can paste this at the start of each conversation, or store it where your tool keeps reusable instructions. ChatGPT, Claude and Gemini all offer ways to save standing instructions or reference files for a set of conversations, and Microsoft Copilot has similar options in business settings. Features vary and tools change, so check what yours offers, and try the same style sheet in two tools to see which follows it more closely for your kind of writing.

Test it, then keep improving it

A style sheet is only as good as the drafts it produces. Test it with three different jobs: a lesson introduction, a short community post and a slightly awkward message such as a price change notice. Read each result aloud. Wherever you find yourself editing the same thing twice, that's a missing rule. Add it.

A few signs your sheet needs work:

• Drafts reuse whole phrases from your examples. Add more varied examples.
• Drafts overdo one trait, such as humor everywhere. Add a note about restraint.
• Drafts sound right but say nothing specific. That's a content problem, not a voice problem, and no style sheet fixes it; your own ideas and examples still have to go in, as drafting member articles without sounding like AI explains.

However good the sheet becomes, every draft still gets a human read before it reaches members. The sheet gets the voice close; you make sure the content is accurate, kind and actually yours.

Your voice style sheet checklist

1. Collect three to five pieces of your own writing that you'd happily show a new member.
2. Run the analysis prompt and read what it says about your voice.
3. Edit the draft sheet by hand: traits, words to use and avoid, formatting and examples.
4. Wrap it in the reusable prompt and store it where you can find it.
5. Test it on three different kinds of content and add a rule wherever you repeat an edit.
6. Review the sheet every few months, and share it with anyone else who writes for your members.