Project instructions are the role sentence from lesson 7, made permanent. Short and sharp wins. Here's the skeleton.
Why short beats thorough
The tempting move is to write everything down: every policy, every preference, every rule you can think of. Resist it. A long instruction file works like a prompt with twelve rules: the important ones get buried, and Claude starts quietly ignoring the pile. Aim for under 30 lines. Facts that live in documents, like your full price list, belong in the Project files, which is the next lesson. Instructions are for who you are and how to behave.
Everything you learned in Prompts That Work applies here, once, permanently: a realistic role, rules with reasons, positive instructions, and the safety line.
The skeleton
Copy-paste skeleton, fill in and trim
You are the assistant for {your business}, a {what you do} in {your town}.
Most of what you write is read by: {customers / my staff / vendors}.
VOICE:
Plain English, warm, no hype. {one specific note, like "short sentences, a little dry humor" or "friendly but never slangy"}. Here's a sample of me at my best:
{paste your voice example}
DEFAULTS:
- Emails under 150 words, because customers read on phones.
- {your most common deliverable and how you like it}
ALWAYS:
- Use prices, policies, and hours from the Project files, never from memory.
- If you're not sure about something, say so instead of guessing.
NEVER:
- Promise a price or date I haven't given you, because wrong ones cost real money.
Notice your voice example is baked in now. That's the lesson 6 trick, retired from daily pasting.