The gap between a useless AI answer and a great one is usually the prompt, not the tool. Six habits close most of that gap.
"You are a copy editor. Tighten this email without losing the point" works better than "fix this". The role tells it what good looks like.
Do not describe the email, paste it. Do not summarize the contract, paste the clause. The tool works on what it can see, and guesses about what it cannot.
A table, five bullets, a ready-to-send reply, a checklist. If you do not pick a format, it picks one for you, and you will not always like its choice.
Paste a paragraph in your style and say "match this voice". One real example beats three paragraphs of describing your taste.
Iterate in short commands: "shorter", "less formal", "add the numbers", "cut the intro". Two or three rounds get you further than one giant perfect prompt.
When the task is fuzzy, end with "ask me whatever you need before answering". The questions alone usually sharpen what you actually want.
Weak: "write a cover letter". Stronger: "You are a hiring manager at a logistics company. Here is my resume and the job ad. Write a 150-word cover letter that opens with the result in my second bullet, in plain English, no buzzwords." Same tool, different universe.
Independent guide. No tool affiliations.