Use negative examples to sharpen output quality

One of the most underused prompt engineering techniques: telling Claude what to avoid, not just what to produce.

Why this works

AI models have learned from enormous amounts of text that includes all the clichés, filler phrases, and overused constructions you want to avoid. Without explicit instructions, they default to those patterns.

When you name the specific patterns you don't want, Claude avoids them much more reliably than when you only describe what you do want.

The most useful negative instructions for sales writing

  • "Do not start with 'I hope this message finds you well' or any similar greeting."
  • "Do not use the word 'leverage', 'synergy', 'circle back', or 'reach out.'"
  • "Do not end with 'Please don't hesitate to reach out.'"
  • "Do not use passive voice."
  • "Do not mention our product features in the first paragraph."
  • "Do not use exclamation marks."
  • "Do not write more than [X] words."

Build a standing 'avoid' list

Keep a running list of phrases and patterns that consistently appear in AI outputs and that you always delete. Paste this list into every prompt as a 'Do NOT use' instruction block. The output quality improvement is immediate.