Although, I am don't want any tutoring if you want to make money whilst teaching people consecutively then you can try making a book and detailing what you did to achieve your grades.

In fact, two days ago, I purchased a book about maths from someone who wasn't really popular but had 18 5-star reviews on his textbook about what he did to gain his perfect grades. Currently, there isn't much people trying out this business model and this guy had only started last year. Be wary though, if you want to try this then don't opt out for downloadable .pdf textbooks as people can easily exploit it and you wouldn't make any income.

A second form of advertising is something I thought of a long time. Many young people use myGCSEscience for science revision however when you watch his youtube videos there is always mistakes which he has to fix with annotations once or twice each video. Also, you can add more detail, on myGCSEscience videos he noted a type of disease caused by something something that I vaguely can recall but it was hard to catch it. What I am trying to say is that you can try do his business model but invest more time into quality and make it more intriguing as his videos can be a little boring. However, if you put in the time then the resources you provide would be good for the long run. Heck, you don't even need to do science videos, do maths since I haven't seen much people do it.

That's is all, however if you want to tutor then advertise properly. I'm not sure about mathematics, but when I was searching for music tutors they often would have these types of approved certificates to verify themselves to not look sketchy. But remember, try to make things affordable as education is essential to everyone and big price tags usually shy people away from potential good products.

Good luck!