Tell it what NOT to do, sparingly

Putting a word in the prompt raises its activation, even when the word is wrapped in 'do not'. The model does not have a clean negation operator the way code does; it has attention, and attention does not know the difference between mention and command.

Rewrite prohibitions as positive descriptions of the target. Instead of 'do not be formal', say 'write like you are texting a friend'. Save the hard negatives for the few rails you cannot express any other way.