1) Don't quit yet. Keep the income coming in while you test the idea.
2) Build the list before you build the product.
3) One landing page. What it is, who it's for, why it's better.
4) Five questions when they sign up: their situation, the outcome they want, what they've already tried, the price, anything else.
5) Post short form every day, pointing at one long video, pointing at the list.
6) Sign-ups aren't clients. Collect ten for every one you need.
7) No audience? Clipboard outside the shop, same questions, real people.
What used to take months and money now takes an evening.
Save this so you've got the steps.