Thanks UV, I've had great luck with Tryst and Domina.ms.

My former owner was an active prodomme for a bit and I helped develop her web presence. She got a surprising amount of hits on her website off of Sinsearch. My reviews of my double domme sessions with her and others (always with the disclosure that she was my owner at the time of course) here and at Max Fisch helped her get web traffic as well, so I think linking to positive reviews of yourself can be helpful because that way clients who are grateful to you might take the hint they should write good reviews too.

Advertising in the Fetlife groups where it's allowed is free, so there's that.

As a client, Tryst has the best search functionality and Dickie Virgin is prolly the most comprehensive listing of dommes who are known to be well-reviewed out there. I also use Mistress-Guide, Models World, and the website formerly known as twitter. I get that there are many good reasons some might be hesitant to get enmeshed in that hellsite, but I think at least a minimal presence there interacting with other well known dommes helps clients who might be looking for signs that you're a real person as opposed to a scammer feel more comfortable contacting you.