HomeCasa Prompts

How to create a prompt from scratch

A 6-step method to go from a vague idea to a clear, reusable prompt, with a complete end-to-end example.

Creating a good prompt is a lot like briefing a person: the better you explain what you need, the better the result. This method works with any text assistant.

Step 1: define the result you want

Before writing, answer: what will I have in hand when the AI is done? An email ready to send, a comparison table, a 60-second script, a Python function…

If you cannot describe the result, the AI will not be able to give it to you either.

Step 2: provide the context only you know

The AI does not know who you are, who you are addressing or what you have tried. Add:

  • Who the result is for (audience, knowledge level).
  • The starting situation and relevant data.
  • What you already tried and why it did not work.

Step 3: assign a useful role

A role steers vocabulary and judgment: “act as an employment lawyer”, “you are a primary school teacher”. It works best when it is specific and relevant to the task. More in how to define roles.

Step 4: write clear instructions

Split the task into numbered steps if it has several parts. Use concrete verbs: list, compare, summarize in 3 points, rewrite.

Step 5: set constraints and format

State the length, tone, what it must not do and how you want the answer. For example: “max 150 words”, “no jargon”, “answer in a table with columns X, Y, Z”.

Step 6: test, review and improve

Run the prompt, read the result critically and adjust. If something fails, it is almost always because context was missing or an instruction was ambiguous. Save the version that works and turn it into a template with variables.

Complete example

Act as a communications advisor for small businesses.

Context: I own a bike shop in Bristol. We are starting to offer at-home
repairs for customers who work from home.

Task: write the copy for a flyer to deliver in the neighborhood.

Instructions:
1. A short headline highlighting the time saved.
2. Three benefits as bullets.
3. How to book the service (phone and website as [FILL IN]).

Constraints: max 90 words, friendly tone, no prices.
Format: text ready for layout, with the headline on its own line.

Quick template

Copy this structure and fill it in:

Act as [ROLE].
Context: [SITUATION, AUDIENCE, DATA].
Task: [WHAT YOU WANT].
Instructions: [STEPS OR CRITERIA].
Constraints: [LIMITS, TONE, WHAT TO AVOID].
Format: [HOW YOU WANT THE ANSWER].

Or use the prompt builder, which generates the final text ready to copy.

Learn prompting

  • What is a prompt and how does it work

    A prompt is the instruction you give an artificial intelligence. Learn its parts, why the result depends so much on how you write it, and how to get started.

  • How to write effective prompts

    Ten practical principles to write prompts that work on the first try more often: clarity, specificity, examples, format and review.

  • How to write prompts for ChatGPT

    Practical tips to get more out of ChatGPT: message structure, custom instructions, long conversations, files and reviewing answers.

  • How to write prompts for Claude

    How to write prompts for Anthropic's Claude: direct instructions, rich context, long documents, tags for structure and requests for reasoning.

  • How to write prompts to generate images

    The structure that works best in Midjourney, DALL-E, Stable Diffusion, Flux or Firefly: subject, style, light, composition and parameters, with examples.

  • How to write prompts to generate videos

    How to describe a shot for Runway, Kling, Sora or Veo: one subject, one action, camera movement, light and mood. And how to plan multi-shot videos.

  • How to improve a bad prompt

    A diagnostic process to find out why a prompt is not working and how to fix it, with a before-and-after example and a prompt to let the AI help you.

  • What are variables in a prompt

    Variables turn a prompt into a reusable template. Learn how to define them, name them and use them on HomeCasa Prompts.

  • What is context in a prompt and how much to give

    Context is the information the AI cannot guess. Learn what to include, what to avoid and how to organize documents and data inside a prompt.

  • How to define roles in a prompt

    What telling the AI “act as…” really does, how to choose a good role, combine it with concrete criteria and avoid roles that do not help.

  • How to structure prompt instructions

    Numbered steps, delimiters, sections and logical order: how to organize a long prompt so the AI does not skip anything.

  • Good and bad prompt examples

    Eight comparisons of real prompts for text, code, image and video, explaining what fails in the bad version and what the good one improves.

  • Common mistakes when writing prompts

    The ten most common prompt-writing mistakes and how to avoid them: from missing context to blindly trusting the answer.

  • Advanced prompting techniques

    Few-shot examples, step-by-step reasoning, prompt chaining, self-critique, structured outputs and evaluation: techniques for more reliable results.