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What you'll accomplish

By the end of this guide, you'll have ChatGPT Custom Instructions configured with a client's brand voice — so every AI-assisted task for that client automatically starts from the right tone, vocabulary, and style, without you having to re-explain it in every prompt.

What you'll need

  • A ChatGPT account (Plus at $20/month for Custom Instructions; free tier has limited access)
  • Your client's brand voice guide, style guide, or a few examples of their approved copy
  • 20 minutes to write the custom instructions
  • Time needed: 20 min setup; saves 10–20 min per client work session
  • Cost: $20/month (ChatGPT Plus)

How-To Guide: Set Up ChatGPT Custom Instructions for Client Brand Voices

Step 1: Gather your client's brand voice details

Before opening ChatGPT, collect these from your brief or brand guide:

  • Tone adjectives (3–5): e.g., "confident, direct, conversational, no-nonsense"
  • Vocabulary rules: Words they use / words they avoid. e.g., "Say 'people' not 'users,' say 'easy' not 'seamless'"
  • Sentence structure preference: Short punchy sentences? Long complex ones? Mix?
  • Things to never do: "Never use exclamation points," "never say synergy or leverage," "avoid bullet lists — use paragraphs"
  • Audience description: Who the content is for, in one sentence

What you should see: A short notes document with these 5 elements captured.