I freelance mix and produce music. The advice I’ve heard from other music freelancers is try to be helpful whenever you can manage it. What allowed me to start receiving clients was getting to know people in my kinda scene and telling people it’s something I enjoy doing. Once I had a few accessible examples of my work I could point to, I started receiving more inquiries. Start offering your services to friends or peers you admire. You don’t have to be sales-y, just offer it as a way you can help them should the need arise.