TL;DR: One founder built a library of 47 battle-tested prompts. These 5 changed his actual workflow, not just his notes app.
Most prompts online are garbage. Too vague, too generic, designed to sound smart rather than work. You ask for help, you get fluff. The model hedges, qualifies, and pads its way to an answer that technically responds to what you asked but doesn’t actually solve anything. The problem isn’t the AI. It’s the prompt. Garbage in, garbage out.
These five are different. A solo founder shared them after running real tests across 200+ prompts over six months of actually running his business. Not a side project. Not a hackathon. Paying clients, real deadlines, real stakes. Each prompt survived because it produced a result he used, not a result he filed away and forgot. Each one is specific, opinionated, and does exactly one job well.
The 5 Prompts
1. The 40% Editor
Prompt: “Rewrite this 40% shorter without losing meaning. Cut filler, redundancy, hedging. Final version only.”
Most writing is 40% air. This prompt finds it and removes it. The phrase “final version only” is doing more work than it looks. It stops the model from explaining every change it made, which would defeat the whole point. Try it on your last proposal, your website homepage copy, or any email you’ve written over 150 words. The first time you run it, you’ll be surprised how little you actually lose. The second time, you’ll stop writing long in the first place.
2. Devil’s Advocate
Prompt: “List every way this plan could fail, every assumption I’m making, every risk I’m ignoring. Brutal.”
One word does all the work: brutal. Without it, the AI softens everything into politeness. It wraps concerns in phrases like “you might want to consider” and “it could be worth thinking about.” That’s not useful when you’re about to spend three weeks building something. The word brutal removes the diplomatic cushion and forces the model to surface the uncomfortable stuff you’re probably already half-aware of but haven’t written down. This is how you stress-test an idea before committing to it. Run it on a pricing page, a launch plan, a new offer, or even a hiring decision.
3. Real Customer Fear
Prompt: “Tell me: the fear my ideal customer won’t admit publicly, the exact language they use to describe the problem to themselves, and what they’ve tried that didn’t work.”
Copy research in 30 seconds. If you write landing pages, ads, or outreach emails, this one will change what you produce. The key is the third part: what they’ve tried that didn’t work. That’s where buying resistance lives. People don’t just want a solution to their problem. They want to know why this solution is different from the last three things they tried that didn’t deliver. Name that in your copy and you stop sounding like everyone else. Pair this prompt with a specific customer type for sharper results: “My ideal customer is a solo consultant who has been trying to grow their pipeline for 12 months.”
4. Plain English
Prompt: “Explain [topic] like a smart non-expert. One analogy. Under 150 words.”
Use this when you need to understand something fast, or explain it to someone who doesn’t care about the technical side. The word limit and the analogy requirement force clarity. Constraints are what make AI output actually useful. Without them, the model defaults to covering everything, which means it covers nothing well. This prompt is also excellent for client communication. When you need to explain why something technical matters to someone who just wants results, run your draft explanation through this prompt first. What comes back will convert better than whatever you wrote originally.
5. Cold Email Surgery
Prompt: “Rewrite this email: open with their problem, one ask under 10 words, under 100 words, zero jargon.”
Cold email is mostly noise. Intros about how you found someone’s LinkedIn, long paragraphs about what your company does, three different questions in one message. This cuts it to what actually converts: lead with their problem, one clear ask, short. The “one ask under 10 words” constraint is the one people skip. Force yourself to keep it. If you can’t summarize what you want in under 10 words, you haven’t decided what you want yet. The email isn’t the problem.
Where These Work Best
- ✂️ Editing and content: 40% Editor, Plain English
- Business planning and decisions: Devil’s Advocate
- Marketing and copywriting: Real Customer Fear, Cold Email Surgery
- Client outreach: Cold Email Surgery, Plain English
Worth noting: these prompts compound. Run your cold email through the 40% Editor after Cold Email Surgery. Use Plain English to simplify whatever the Devil’s Advocate surfaces. The prompts work alone and they work better together.
Prompt of the Day
Drop the Devil’s Advocate prompt on something you’re currently planning or building. Read what comes back. If something surprises you, you needed to know before you shipped. If nothing does, the prompt still did its job. It means you’ve already thought it through. Either way, you’re more confident in what you’re doing next.
What’s Your Go-To?
Drop your most-used prompt in the comments. The best ones tend to be short, specific, and a little uncomfortable. If it feels a little aggressive when you write it, it’s probably working.
5 prompts that actually changed my workflow (after testing 200+)
by u/SirDePseudonym in PromptEngineering