Co-incidentally, I ran a content creation business virtually, and had the same problem. You need to identify clearly who your audience is depending on the type of content you produce. So if you make infographics, maybe a highly technical data driven client that is looking to present their content in a more interesting manner would be an ideal match. Then when you do find out who your ideal client is, if they're in the B2B space, I'd say email marketing works well. You'd have to reach them on email to figure out if they'd like your services. You might need to email about a 1000 people to even just get a couple of leads, like 2 or 3 that actually become paying customers. I'm happy to jump on a call and share more information if you'd like.