How to write an effective prompt: the 5 rules that actually change the answers
The quality of what you get from an AI assistant depends almost entirely on how you ask. Five practical rules, with before-and-after examples.
A prompt is simply the message you write to an AI assistant. Many people treat it like a Google search: three words and go. The result is a generic answer. The five rules below work with any assistant and, put into practice, make the difference between a mediocre reply and a genuinely useful one.
1. Give context before the request
The model does not know who you are or why you are asking. Before: “Write an email to the client.” After: “I’m an IT consultant. I need to email a client who paid 40 days late, keeping a friendly tone because I want to keep working with them.” The second version produces an email you can send almost as is.
2. Specify the format you want
Do you want a list, a table, a 100-word paragraph, a JSON file? Say so. “Answer with a three-column table: product, price, pros and cons” saves you a second request just to reformat.
3. Show an example
If you have a style in mind, paste an example and ask for it to be imitated. “Here’s how I usually write product descriptions: [example]. Write the description of this new item the same way.” One example is worth ten adjectives.
4. Ask it to reason step by step
For logic problems, calculations or decisions with several variables, a phrase like “reason step by step before giving the final answer” measurably reduces errors, because it forces the model to make its path explicit instead of jumping to the conclusion.
5. Iterate, don’t start over
The first answer is a draft. Instead of rewriting everything, correct it: “Shorter”, “Drop the second paragraph”, “Less formal”. The model remembers the conversation and every pass improves the result.
A common mistake to avoid
Don’t ask “can you do X?”: the model will answer “sure” and then wait. Ask directly: “do X”. And if the answer contains numbers, dates or quotes, verify them: assistants can invent details with great confidence.