It is important that after thinking in the product/service and the business model, you come up in a way to combine them.
I will set the business idea I want to develop.
I took the approach of the Product/Service first. Thinking in my personal Strengths, I speak Spanish fluently. So I decided to provide Spanish services. Now, how can I make money online with that ability?
Business Models that could fit it are:
Ads, I can create a free Spanish teaching site with ads to create revenue.
Affiliate, I can create the learning Spanish site and suggest learning materials, those links would be in my site and when the visitors buy them I receive a percentage.
Subscription, I can sell my lessons. Visitors would need a membership to access them.
Merchant, I can do translations and charge for them.
I hope you can see that any ability has many ways to monetize it. And many business model can fit them. And what is best, you don’t have to pick just one. You can have many ways in your site to make money.
Just be careful, start with one, and them incorporate others, you want to be the best if you want people to prefer you.