In this article
- What is a ChatGPT prompt?
- Where do prompts live in ChatGPT?
- How do I get a better answer after a bad one?
- What do I say when ChatGPT does the wrong thing?
- When should I use thinking mode, search, files or voice?
- How do I use Projects well?
- Is ChatGPT the right tool for every prompt?
- How to prompt ChatGPT: questions people ask
The short answer
To prompt ChatGPT well, put standing rules in custom instructions, ongoing jobs in Projects and the task itself in the chat. Paste the real material, ask for a specific format, then steer with short follow-ups. Expect to use three turns: draft, fix the biggest flaw, polish.
Most ChatGPT advice is about what to type. Almost none of it mentions that ChatGPT has four different places to put instructions, and that using the right one saves more time than any clever phrasing.
This guide is organised the way ChatGPT is: from the things you set once, down to the single message you are about to send. Features and menu names move around, so check them against what you see on screen. The thinking behind them stays put.
What is a ChatGPT prompt?
A ChatGPT prompt is anything you type, say or upload to ChatGPT to tell it what to do. It can be a question, an instruction, a document or a mix. ChatGPT reads the whole conversation each time, so every earlier message is part of your prompt.
Where do prompts live in ChatGPT?
Think of four layers, from permanent to one-off. Put each instruction in the narrowest layer it belongs to.
| Layer | What it is | Put here |
|---|---|---|
| Custom instructions | Standing rules applied to every chat | Who you are, spelling, tone, what to avoid |
| Memory | Facts ChatGPT keeps from past chats | Stable details: your role, your clients' sectors |
| Projects | A workspace with its own files and instructions | One ongoing job: a client, a campaign, a book |
| The chat | The task in front of you right now | The actual request and the material |
I work in [your field] at a small UK business. Use British English and plain words. Keep answers short unless I ask for detail. If you are not sure about a fact, say so instead of guessing. Never use exclamation marks. When I ask for a draft, give me one version, not three. Ask me a question if my request is too vague to do well.
Tip: three or four rules you will really follow beat twenty you will forget. Rewrite it after a month.
Memory is handy and also worth a look. Open it occasionally and delete anything out of date or anything you would rather it did not hold. That is also good practice before you share a screen in a meeting.
How do I get a better answer after a bad one?
Use the three-turn rule. The first answer is a rough draft, the second fixes the biggest problem, the third polishes. Almost nobody needs a fourth. Here is how it looks on a real job.
Write a short email to a customer who has complained that our delivery was two days late. Their name is Sam. We have already refunded the delivery fee.
Too stiff. Sam is a regular customer and we know them. Make it warmer, cut the apology to one sentence, and lead with the refund.
Good. Now trim it to 80 words and give me three subject line options that do not mention the word 'apology'.
Notice that none of the follow-ups restates the task. You are steering, not starting again. Pushing back in a short, specific sentence works better than rewriting the lot.
What do I say when ChatGPT does the wrong thing?
| If it... | Say |
|---|---|
| Rambles | Cut that by half and keep only what changes my decision. |
| Sounds like a brochure | Rewrite as if you were explaining it to a friend over a pint. |
| Invents a fact | Which of those claims did you not get from the material I gave you? Remove them. |
| Agrees with everything | Now argue the opposite case as strongly as you can. |
| Ignores an instruction | You missed this rule: [rule]. Redo it, following that rule. |
| Gives a vague plan | Turn that into specific steps with who does what by when. |
When should I use thinking mode, search, files or voice?
ChatGPT has several modes, and the names change, so judge by the job.
- A slower, thinking option for hard problems: maths, logic, planning, anything with several moving parts. For a quick email it only adds waiting time.
- Search for anything recent or checkable. Ask it to cite sources and then click two of them. Often, a link says less than the summary claims.
- File upload when you have the real document. Ask for answers "only from the attached file" and request page references.
- Voice for thinking out loud on a walk. Ask it to turn your ramble into bullet points afterwards.
Using only the attached contract, list every date and every payment obligation, with the clause number for each. If something is not in the document, say 'not stated' and do not fill the gap from general knowledge.
How do I use Projects well?
A Project is a folder with a memory. Give each ongoing job its own, drop in the reference material once, and write instructions that apply to that job only. When you come back in three weeks, ChatGPT already knows the brief.
This project is for Harbour & Co, a family-run chandlery in Poole. Their customers are sailors aged 40 to 70. Tone: friendly, dry, practical. Never use nautical puns. The attached brand guide and price list are the source of truth. When I ask for copy, give me one version and flag anything you had to assume.
Is ChatGPT the right tool for every prompt?
No. ChatGPT is a good all-rounder. Claude tends to be stronger at long documents and careful writing. Copilot has the edge when your work lives in Microsoft 365. Perplexity is built around search. Our side-by-side on Claude vs ChatGPT and the note on ChatGPT vs Copilot for business will help you pick.
How to prompt ChatGPT: questions people ask
What is the best way to prompt ChatGPT?
Give it the real material, say who the output is for, choose the format and set a few limits. Then steer with short follow-ups rather than starting again. Put rules you always want into custom instructions so you do not repeat them.
What should I put in ChatGPT custom instructions?
Your role, your spelling and tone preferences, what to avoid and how long answers should be. Keep it to a handful of rules you will genuinely stick to, and review it every month.
What is the difference between memory and Projects?
Memory holds facts about you across chats. A Project is a workspace for one job, with its own files and instructions. Use memory for stable background and Projects for ongoing work.
Why does ChatGPT make things up?
ChatGPT predicts plausible text rather than looking facts up, so it can sound sure while being wrong. Paste your sources, ask it to say when it is unsure and check anything that matters. See how to judge the accuracy of AI information.
Is it safe to put company data into ChatGPT?
Only if your plan and your policy allow it. Free and personal accounts handle data differently from business plans. Write a short AI policy first. Our AI Policy Workshop does this in a session.
Where can I learn ChatGPT properly?
Start with ChatGPT for Dummies, then consider ChatGPT training for your team.
Keep reading
Get your whole team prompting ChatGPT the same sensible way
Our ChatGPT training works on your team's actual tasks, so the prompts they leave with are the ones they will use on Monday.
- Prompts, Context and Skills Deep Dive A half day on Claude and ChatGPT prompting.
- Basic AI Training The calm start for beginners.
- ChatGPT for Dummies Plain-English guide, no jargon.
Harry Lang
Harry Lang founded The Oxford AI School in Witney, Oxfordshire. He trains UK businesses and teams to use AI well, writes the Marketing Unfiltered newsletter, and is the author of Learn To Fly With AI.