Using ChatGPT to write sales posts: why they all sound the same, and what to tell it
A maths tutor opens a new course and asks ChatGPT for a sign-up post. Every line is polished and nobody gets in touch. The problem isn't the AI. It's everything she didn't tell it.
Key points
- AI-written posts sound alike because, given little to go on, AI fills the gaps with the words most businesses use.
- A good prompt covers four things: who the reader is and what worries them, concrete facts, what you do differently, and how your shop talks.
- Listing words the AI must not use works better than asking it to "make it sound unique".
- Showing AI your past posts that got lots of messages helps new posts sound like your shop.
- Always check an AI draft for prices, dates and promises, because AI can add details you never gave it.
Sunday evening. A private maths tutor has just decided to open a new course: exam prep for students moving up to upper secondary, six to a group, Saturday mornings, four months before the exam.
She opens ChatGPT and types, "Write a sign-up post for my maths tutoring course." In under a minute she has a long post full of emojis. It opens with "A quality maths course that will lead your child to success", then promises expert teaching, a friendly atmosphere and rich content.
Nothing in it is wrong. But scroll through other tutors' pages in the same area and you find nearly the same sentences, word for word. Two days after posting, three people have liked it. One of them is her mum.
Most people decide at this point that AI can't write. Look closer, though, and it did everything it was asked. It just wasn't asked for much.
AI posts all sound the same because we tell it too little
AI writes from what it has read before. Give it one line and it fills the rest with what most tutoring courses say. What comes out is the average of every sign-up post ever written.
Words like "quality", "friendly" and "expert" are the traces of that gap. They fit every business, which is exactly why they say nothing about any particular one.
Readers feel it even if they can't say why. A post like this has nothing wrong with it, and nothing to remember either.
What your business knows that AI never can
Imagine describing the course to a friend who has never seen your classroom. You wouldn't say "quality". You'd give details, and those details are what the AI needs.
Who's reading, and what's worrying them. The people who sign kids up for tutoring are parents, not kids. And what parents are worried about right now is that there are only a few months left and their child still can't do word problems. Not some vague wish for their child to succeed.
Facts you can picture. Six per group. Saturdays, 9 to 11, sixteen sessions. A past exam paper every week, with scores sent to parents on LINE. Details like these do all the work the adjectives were trying to do.
What you do differently. It might be small, like making each student explain their thinking out loud before she gives the answer. The things an owner thinks of as "just how I've always done it" are often things customers have never seen anywhere else.
How your business sounds. Do you talk to customers like an older sibling, like a teacher, or with a clinic's politeness? If you don't say, the AI picks for you, and it tends to pick advert voice.
What a prompt with enough information looks like
Put all that into a prompt (the instruction you type to the AI) and it's many times longer than the original one-liner. It still takes under five minutes to write.
Write a Facebook post for a maths exam-prep course. The readers are parents of students about four months away from their upper-secondary entrance exam, who are worried their child still can't do word problems.
Course details: 6 students per group, Saturdays 9:00-11:00, 16 sessions, a past exam paper every week, scores sent to parents on LINE, and the tutor has students explain their reasoning before every answer.
Write it as a tutor talking to parents: polite but not stiff, under 120 words. Don't use the words quality, expert or friendly. No emojis. End by inviting them to message on LINE to ask about class times.
Notice it says what you don't want as well as what you do. Banning tired words outright works better than asking it to "make it sound unique", because the AI doesn't know what the tutor down the road wrote, but it does know which words it isn't allowed to use.
The post you get back talks about what parents are actually worried about from the first line, because you've told it who's reading.
Show AI your past posts that sold, so it hears your voice first
If you've had posts that brought in lots of messages, those are the best examples you can give the AI. They work better than trying to describe how your business talks.
Here are 3 posts from my page that got lots of people messaging me. [paste posts] First tell me what tone they use, how long the sentences are and how they open. Then write a new post about my school-holiday course in the same style.
Asking it to describe the style first is more useful than it sounds. Sometimes that's the moment an owner learns that their posts that worked tend to open with a question parents ask, or tend to tell the story of one student in the class.
Keep the prompts that work in a note on your phone. Next time you only change the course details instead of starting from scratch.
The first AI draft is raw material, not a finished post
However much you tell it, the first draft still needs to go through your hands. At the very least, check prices, dates and anything it promises customers. AI can add things that aren't true with complete confidence, like "guaranteed exam results" when the tutor never said anything of the kind.
If it still reads too much like an advert, you don't have to rewrite it yourself. Keep instructing it.
Give me 3 versions. The first opens with a question parents often ask. The second opens with something that happened in class. The third is the shortest, under 50 words. Cut every adjective that isn't backed up by a fact.
Asking for several versions shows you which angle suits your business, and then you can pull the best lines from each. The best post is often a blend that the owner tweaks by a few words.
If you're not sure where AI fits in your business yet, AI for small businesses: what it's actually good for is a good place to start.
The line readers remember comes from a real classroom
AI can put words in order quickly, but what makes a post sell is still a story only your business can tell. A tutor who watched one student stop being scared of word problems in the sixth session has something AI will never come up with on its own.
If you want stories like that to last longer than a post that scrolls away in a feed, writing them up as articles on your own website lets people find them later on Google. Shops with a woowey website have an articles page we've already set up for SEO. Owners can edit the text and photos themselves or tell the AI assistant what to change in Thai. The story itself stays theirs.
The tutor's new post opened with the one line AI didn't write for her: "Four months to go, and my child still reads a word problem and has no idea where to start." Plenty of parents had said exactly that to her already.
Frequently asked questions
How do I prompt ChatGPT to write a sales post?
Cover four things: who the reader is and what worries them, the concrete facts about your product or service, what makes you different, and the tone you want. Then list any words you don't want it to use.
Why do AI-written posts all sound the same?
With little information, AI fills the gaps with words most businesses use, like "quality" or "friendly". The more specific detail you give about your business, the more your post stands apart.
Can I post what AI writes without editing it?
Always read and edit it first, especially prices, dates and promises to customers, because AI can add details you never gave it.
Is ChatGPT or Gemini better for writing captions?
For writing posts, ChatGPT, Gemini and Claude perform similarly. The result depends far more on the information you give it than on which one you pick.
The woowey team
We build websites and systems for businesses
We build websites, booking systems, online stores and back offices for Thai businesses, then look after them every month. What we write here comes from what we see working with real shops.
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