You don't need a hundred design prompts. You need five you trust and actually reuse.
Start with the smallest version
Treat the first output as a draft, not a verdict. The prompt does the typing; you keep the judgment about what ships.
Anchor to one reader
Ask for the reasoning, then the result. When the model shows its steps you can see exactly where to push back.
Write down what you never want as explicitly as what you do. The exclusions often do more work than the instructions.