What Is The Best Way To Find/Prospect For SEO Clients?

Hello everyone, so I've recently landed my first few clients in SEO but since then I've had some trouble. I use a lot of Instagram, Facebook, and even email marketing but the responses aren't always the greatest. I wanted to know where and how you guys go about prospecting? I know some people really enjoy or find success in cold calling; however, I truly felt that I wasn't seeing results that way and reached less people.