Practice10 min read

System Prompts and Persona-Setting

Set the stage once, save it forever

If you find yourself writing the same context at the start of every conversation — "You're a marketing strategist, our company is X, our audience is Y, we don't use jargon" — there's a better way.

Most AI tools let you set a system prompt (or "custom instructions," or a project/GPT persona). This is context that applies to every message in a conversation, without you having to retype it. Done well, it changes AI from a generalist into something that feels custom-built for your work.

What goes into a strong system prompt

Five ingredients:

Role — what AI is in this context ("You are a senior marketing strategist for a B2B SaaS company")

Domain context — what AI needs to know that doesn't change ("Our product is X. Our typical customer is Y. We sell against competitors Z.")

Voice and tone — how AI should communicate ("Be direct. No fluff. Use specific examples, not abstract advice.")

Output preferences — how AI should format responses ("When I ask for a recommendation, give the conclusion first, then the reasoning. Bullet points over paragraphs.")

Constraints — what AI should never do ("Never invent statistics. If asked for data you don't have, say so. Never use the words 'leverage,' 'synergy,' or 'unlock.'")

Inside a conversation set up this way, your prompts get dramatically shorter — you only specify what's new about THIS request.

Constraints are the most underused ingredient. Most people list what AI should do. Listing what AI should NOT do is often more powerful — it cuts out the bland defaults that you'd otherwise have to edit out of every response.

Practice Exercise

You're an HR Business Partner at a mid-sized tech company (~400 employees). You use AI multiple times a day for: drafting performance review feedback, advising managers on tricky people situations, writing communications about policy changes, and summarizing employee survey results. Every time you start a conversation, you type the same context: who you are, your company size, what you DO and DON'T want (no boilerplate HR-speak, no generic advice, always weigh legal risk). Write a system prompt you could save once and use forever.

No pressure — just give it your best shot! Write a prompt for the scenario above and our AI will give you friendly, specific feedback on how to improve.

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(try writing your own prompt first!)