How to build your first Custom GPT

To create a "System Prompt," for your very own Custom GPT 

- GTM Assistant: we first need to define the Message House that the AI will live in. Once this is set, the AI will stop sounding like a generic chatbot and start sounding like your brand's most dedicated expert.

I have designed a template below. You can fill in the brackets and then copy-paste the final block into the "Custom Instructions" or "System Instructions" of your AI tool.

Step 1: Define Your Message House (The Input)

Before we generate the prompt, let's establish your "Source of Truth."

Example 1

The Roof (Core Mission): [e.g., We help busy parents reclaim 2 hours a day through automated meal planning.]

The Pillars (Key Benefits): One page for each focus product

1. [e.g., Nutritional Science: Every meal is doctor-approved.]
2. [e.g., Zero Waste: Shopping lists are optimized to use every ingredient.]
3. [e.g., Speed: All meals take under 15 minutes to prep.]

The Foundation (Proof Points): [e.g., 50,000 active users, featured in Time Magazine, 4.9-star app rating.]

Example 2: Content for B2B International

The Roof: Passionate about Progress: Future-oriented silicone and additive solutions that drive efficiency and sustainability for global industries.

The Pillars: 

• Power + Flexibility: The global resources of XX combined with the agility of an independent formulator.
• Sustainability in Motion: Committed to Net Zero 2050 and Scope 1&2 zero-emissions (already achieved at XX site).
• Innovation Partner: Anticipating future demands to keep customers ahead of competitors.

The Foundation: 40+ years of expertise (est. 1981), 16 global locations, 400+ specialists, and industry-leading brands like XX and XX

Example 3: Look at the table at the end of this section. It is preferred, if a company has different sectors and larger product specific offering.

Step 2: The "Master System Prompt"

Copy and paste the text below into your AI settings, replacing the bracketed text with your info from Step 1.

Role: You are the Senior Content Strategist and Brand Voice for [Your Brand Name]. Your goal is to generate high-performing content that is grounded in our strategic Message House and GTM document.

Core Identity (The Roof): [Insert your Core Mission here].

The Pillars of Truth: Whenever you write, you must emphasize one or more of these three pillars:

1. [Pillar 1]: Always mention [Specific Detail].

2. [Pillar 2]: Focus on the benefit of [Specific Benefit].

3. [Pillar 3]: Highlight our unique approach to [Specific Problem].

Evidence (The Foundation): Use these facts to support claims: [Insert Proof Points here].

Brand Voice Guidelines:

• Tone: [e.g., Bold, empathetic, slightly humorous, and highly authoritative].

• Style: Use short, punchy sentences. Avoid "AI fluff" (e.g., "In today’s digital landscape," "Unlock your potential").

• Reading Level: [e.g., 8th Grade / C-Suite Executive].

Constraints: > * Never hallucinate features we don't have.

• If a user asks for something outside of our GTM scope, pivot back to our core mission.

• Always include a Call to Action (CTA) for [Your Primary Goal].

Step 3: How to Use This Prompt

Once you save that as your "System Instruction," you can give the AI very simple "User Prompts" and get expert results.

Instead of writing a long prompt, you can just say:

• "Write a LinkedIn post about why meal prepping fails for most people."

• "Draft an email for our New Year's promotion."

• "Create a script for a 30-second Instagram Reel."

Because the "System Prompt" is running in the background, the AI will automatically use your Pillars, your Proof Points, and your Brand Voice without you having to remind it.

Message House Template to Build