How to train your own ChatGPT.

A step-by-step guide to Custom GPTs.

Custom GPTs should be the best thing of ChatGPT.

1. You give it a “pre-prompt” as instructions it must follow before the chat.

2. You give it knowledge it must know before the chat.

For example:

1. Custom instructions on how to write the best contracts.

2. A long PDF of “best written contract” from a trusted source.

3. Now as soon as you start a chat → perfect contracts, instantly.

You can duplicate your taste & experience in one “GPT” anyone can use (or you keep it private). You can even share them online, and get as much as 800,000+ users!

This is my most-used GPT, available for free.

The opportunities are endless…

☑ I know how to create good briefs? I train a GPT my team can use.

☑ I know how to write good headlines? I train a GPT my team can use.

☑ I know how to search good content ideas? I train a GPT my team can use.

But it had one very big problem: the model.

You know that ChatGPT has many models, that I can summarize quickly as:

• o3: best to reason complex tasks.

• gpt-4.1: best for quick tasks.

• gpt-4.5: best to write.

You almost always want to pick o3 over any other model.

But custom GPTs used to not only support gpt-4o (the worst model).

And this is over. You can now select any model.

Here’s my step-by-step guide on:

1. Creating a custom GPT the right way.

2. Selecting the right model, the right way.

3. Finally going beyond simple copy & pasting prompts.

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#1 - How to create your GPT.

Top left menu opener → Click on “GPTs”.

Click on “+ Create”.

You end up on this menu to customize your GPT:

1. Name: just pick any name.
   Useful when share publicly / when you create a lot of them.

2. Description: a one-liner explaining what’s the GPT doing.
   Again, very useful when shared to a team / navigating.

3. Instructions: the prompt before the chat.
   Most important part of the GPT. I will write a whole section on it.

4. Conversation starters: to give an example of a first message.
   I usually do “Click here” or leave it blank.

5. Knowledge: where you upload documents that the GPT can read and use to answer questions based on their content. It’s context or examples.

6. Recommended model*: newest addition. Choose the model.
   o3 for reasoning / gpt-4.1 for quick tasks / gpt-4.5 to write

7. Capabilities: which ChatGPT feature you want to turn on.
   Just select everything.

8. Actions: to connect external tools.
   So it can do things—like search the web, send emails, fetch data, or run code; beyond just chatting. Too technical for now for people like us.

Let’s build one together.

#2 - Hook Generator GPT

So far, I gave it a name “Hook Generator GPT” and a description “to write better hooks”. For 3) Instructions, now comes the real work.

I usually start like this:

• I open my Prompt Maker.

• I explain very simply the prompt I need.

• I test it, change the prompt if needed, until I enjoy it.

Make sure to use “o3” inside Prompt Maker.

I shared this prompt to simply describe what I need, with an example:

I want a prompt to write hooks for my social media post.

1 - only sentences below 55 characters

2 - hooks are 2 lines (with a line break in between)

3 - the first line must make you feel something negative (like a gap)

4 - the second line must be an invitation to read more

For example:

///

You don't know how to do SEO anymore.

But this one thing ruins your website:

///

And my GPT “Prompt Maker” gave me a solid first prompt (our chat is here).

I kept iterating like this:

Now I can copy it, and paste it on our GPT panel from before:

For conversation starters, I often time do this:

The reason why is that I tend to forget how to use each and every GPT. But when you just “Start”, the GPT will explain to me what to do.

The “Knowledge” part is quite important: here, I would simply compile my favorite hooks on a txt. file from a google doc. Like this for example: https://docs.google.com/document/d/1PiJ7IFSy0T466SokEr-QWb1j4s1_nNyZdbDzV9T7TOM/edit?usp=sharing.

Now you can simply:

1. Create it (top right). Select on the “GPT Store”.

2. Test it using the GPT link, like: https://chatgpt.com/g/g-685d6f8f1c048191907f3e0cfd2b0dbf-hook-generator-gpt.

3. Update it until it works! And so far, it’s already working for me.

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This blog is getting too long for Gmail to support it.

And 52% of you told me last week you would love to pay to see me going through my guides on video.

So I’m preparing a paid version of this blog with a weekly walkthrough.

52 weeks. 52 guides to master AI, with English not code.