The best ways to make money, are products where you make something once, and then can keep reselling it.
An online course would be something that you only have to make once, but can sell access to it. Think about it, there are millions of people that potentially are willing to pay for what you know.
You will need to do due diligence and validate your course idea.
A course entitled “Best way to organise your cleaning products” will be very unlikely to have mass appeal.
However you might do better with “How to organise your life to get more done”.
A good starting place is Udemy’s course creation page.