Custom GPTs: how to create one for your company

A business Custom GPT is ChatGPT pre-configured with your knowledge base, your rules, your tone and formats. It becomes an assistant available 24/7 for the team. Setup: 2-4 hours. Maintenance: 30 minutes/month. Here's how to create one that's actually useful.

The 5 highest-ROI use cases for SMEs

1. Sales FAQ assistant: answers questions about services/products before first human contact
2. Quote generator: salesperson pastes client brief, GPT produces structured quote draft
3. Onboarding new hires: answers the 100 most frequent first-month questions
4. Tier 1 customer support: handles repetitive requests, escalates only complex cases
5. Multi-channel content generator: given a topic, produces email + LinkedIn post + social caption

Base setup in 4 steps

Step 1: Define the persona

Name, role, voice. Example: "You are Sarah, sales consultant at Smith Firm. Tone: warm professional, never excessively casual. Always proper English."

Step 2: Upload knowledge base

In files: service brochure, price list, FAQ, case studies, company glossary. Preferred format: PDF or Markdown. Keep under 20MB total for optimal performance.

Step 3: Write specific instructions

Example:

You are the assistant for Smith Firm (accountant, London).

STRICT RULES:
- Answer only commercial/tax questions
- For legal advice, always say "needs personalised consultation"
- Never quote specific prices (always offer free call)
- Max 150 words per reply

WHEN TO ESCALATE:
- Client asks for personalised quote
- Question outside your knowledge base
- Urgent/complaint tone

OUTPUT FORMAT:
- Direct answer
- 1 relevant link to /en/contact/ landing if appropriate
- Never promise specific results

Step 4: Test with real cases

Before deployment, simulate 20 real questions (5 easy, 10 medium, 5 tricky). Verify:

• Consistent tone
• No hallucinations (made-up numbers/data)
• Correct escalation on complex cases
• Appropriate links and CTAs

How to deploy

• Internal to team: share Custom GPT link (Plus/Team users only). Fast, free.
• On website: needs API integration. Developer setup ~€800-2,500, but becomes public (lead gen).
• On WhatsApp/Telegram: via n8n + OpenAI API. Setup ~€500-1,500.

Monthly maintenance (30 min)

1. Review the 30 most recent conversations
2. Add 3-5 answers to new questions (to knowledge base)
3. Update instructions if there are error patterns
4. Update brochure/prices if changed

Want a professional Custom GPT setup? Included in AI Email Boost €890.

Want to apply this to your SME?

If you'd like a concrete analysis of your situation, request the free audit from Gamerbit. In 48 hours we tell you exactly where you're losing leads, time or budget — no sales pitch.

For a complete system, the 2026 no-brainer offers are the most direct starting point.