You will be able to produce a short guide that gets an assistant writing closer to how you write.
Jun Wei manages accounts for a corporate training provider, and most of her day is email: confirming dates with HR teams, sending proposals, chasing feedback forms. When she first tried an assistant on these, the drafts were fine and also obviously not hers. They opened with "I hope this email finds you well", which she never writes. They said "delighted" where she would say "glad". One client replied to an AI-drafted email by asking if she was all right, because it sounded so formal.
The fix is not a better one-off prompt. It is a short description of how you write that the assistant reads every time. This lesson shows you how to build that description, which we will call a voice guide, from your own writing.
Lesson 2.2 of Working with AI assistants, Style samples and examples of what to avoid, showed that a sample of the style you want works better than a description of it. A voice guide builds on that. Instead of pasting samples into every request, you analyse a set of them once and keep the result.
Collect five to ten pieces of your own writing that you would be happy for anyone to read. Choose the kinds of writing you want help with: client emails, internal updates, short reports. Variety helps, so include a reply, a request, an update and something with bad news in it if you have one. Pick pieces you wrote yourself, without heavy editing from a manager.
Before they go anywhere, remove anything confidential. Use the redaction method from lesson 2.4: placeholders for names and companies, figures removed or rounded. Your style survives redaction perfectly well, because it lives in how you build sentences, not in who you are writing to.
Paste the redacted samples into your approved assistant and ask it to describe how you write. Be specific about what you want described: typical sentence length, how formal you are, how you open and close emails, words and phrases you use often, how you ask for things, how you deliver bad news, and anything you seem to avoid.
The description that comes back will be partly right. Assistants tend to flatter, so expect words like "warm" and "professional" that fit almost anyone. Push for the concrete. Ask for examples from your samples behind each point, and ask what distinguishes your writing from a generic business email.
Now read the description critically. You know your writing better than the model does. Delete the flattering generalities. Correct anything that is wrong. If it says you use semi-formal greetings and you always write "Hi" followed by a first name, say exactly that.
Then add the habits you want the assistant to avoid. This is often the most useful part of the guide, because assistants have strong defaults of their own. Stock openers such as "I hope you are well", phrases like "please do not hesitate to contact me", exclamation marks scattered for enthusiasm, and sign-offs you would never use all belong on that list. Write them down specifically.
Jun Wei's finished guide, under 200 words, read in part:
I write short emails, usually under 120 words, in sentences of ten to fifteen words. I open with "Hi" and the first name, then go straight to the point in the first line. I use "glad", "thanks" and "shall we", never "delighted", "kindly" or "please do not hesitate". When there is a problem, I say so in the first two lines, then what I will do about it. I end with one clear next step and sign off "Best, Jun Wei". No exclamation marks, no "I hope this email finds you well", no bold text in emails.
It is plain and specific, and every line is something the assistant can follow.
A guide you have to remember to paste in will be forgotten by Wednesday. Save it where the assistant reads it automatically. Lesson 6.1 of Working with AI assistants, Custom instructions: what to say once, and lesson 6.2, Projects: a workspace for each recurring job, covered the two usual places. Custom instructions apply to everything you do in the assistant. A project applies only to the work inside it, which is better if you also use the assistant for things where your email voice is wrong, such as formal reports.
Then test it. Ask for a draft of an email you have already written and compare the two. Where the draft still sounds wrong, ask what in the guide would have prevented it, and add a line. Two or three rounds usually get a guide that produces drafts you only need to adjust, rather than rewrite.
Keep the guide short. Past about 200 words, people start writing rules that contradict each other, and the assistant tries to satisfy all of them and sounds stiff again.
Collect your samples first, then follow the steps above to build and save your own guide.
Produce a voice guide of under 200 words from at least five samples of your writing and save it where your assistant will use it.
Junxiong-WFG Organisation is an authorised representative of AIA Financial Advisers Private Limited (Reg. No. 201715016G).