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Common Prompting Mistakes (and How to Avoid Them)

The output of a Large Language Model is only as good as the instruction you give it. Yet, in practice, we often see developers and users falling into the same traps. Here are 8 common prompt engineering mistakes and how to solve them.

1. Formulating a vague or too general goal

If you are not specific, the model will fill in the gaps itself. This often leads to generic, superficial output that doesn't quite align with your use case.

BadWrite a code script for AI.
BetterWrite a Python script that uses the OpenClaw API to implement a RAG pipeline with vector search. The data consists of PDF documents.

2. Leaving out essential context

LLMs have no implicit knowledge of your specific situation. Without background information, it is impossible for the AI to give accurate or safe advice.

BadHow often should I change the water in my aquarium?
BetterI have a 450-liter tropical aquarium with a high stocking density of cichlids and angelfish, and I use an ozone system. How often and how much water should I change to maintain optimal water parameters?

3. Cramming too many tasks into one prompt

When you ask a model to simultaneously analyze data, devise a strategy, write code, and format text, the quality of each individual part drops drastically. Break down large tasks.

BadCome up with a plan for renting out AI computing power, write the corresponding website in HTML/CSS, and create a marketing email right away.
BetterWrite the HTML and inline CSS for the dashboard of a platform where developers can rent high-performance AI computing power. Use a minimalist, modern design.

4. Not specifying an output format

Do you need data for an application? If you don't specify exactly which format (such as JSON, CSV, or YAML) you want to receive it in, you will likely get a mix of plain text and code blocks back.

BadGive me some test data for stocks.
BetterGenerate a JSON array with 5 objects containing fictional trading data for backtesting a paper trading bot on Alpaca or eToro. Use only the keys: "ticker", "price", "volume", and "timestamp".

5. Negative instead of positive instructions

Models focus heavily on the words in your prompt. If you say "do not use complicated words", the AI focuses its attention precisely on 'complicated words'. Instead, tell the model what it should do.

BadWrite an introduction, but don't make it too long, avoid jargon, and do not use a formal tone.
BetterWrite an introduction of maximum 3 sentences. Use B1 language level and a lively, informal tone.

6. Ignoring the power of "Few-Shot" examples

The concept of 'zero-shot' (asking something without examples) works for simple tasks, but for complex formatting or data registration, one or two concrete examples (few-shot) are worth their weight in gold.

BadExtract the contact details from this text and format them nicely.
BetterExtract contact details from the text. Use exactly this format:
Name: [Name]
Email: [Email]

Text: "Hi, I am Ivo and my email address is [email protected]."

7. Not configuring the role (Persona)

By default, an LLM responds as a helpful, general assistant. By assigning a specific role or persona, you enforce a certain level of expertise and language style.

BadLook at this code and tell me what is wrong.
BetterYou are a senior Full-Stack Developer with 15 years of experience building scalable applications with Claude Pro and DeepSeek. Analyze the following code specifically for performance bottlenecks.

8. Too rigid and over-specified constraints

Sometimes developers try to force the model into too tight a straitjacket with arbitrary rules, which comes at the expense of the fluency or logic of the response.

BadWrite an essay of exactly 432 words, with 5 paragraphs, where each paragraph starts with the letter A.
BetterWrite a concise essay (about 400 words) about investing in a home HPC setup versus a heat pump. Use a clear introduction, three core arguments, and a conclusion.

Ready to dive deeper?

Writing perfect prompts is an iterative process. Always check your results and adjust where necessary. For more advanced strategies, check out our comprehensive guide on advanced prompt techniques.