Okay, that was just as useless an answer as the porn one, but I am still surprised that my crappy Skyrim-fanart is still being favorited on DA almost weekly, while better pieces just sit there catching dust. I can kind of understand it though, seeing your favorite character represented by artists is fun.
Things that might actually be of use to you could be;
- Put the links in signatures. You don't have to be very prominent about it, but just having your page below every post might just invite people to click on it. Maybe a small banner above it, giving a glimpse of what to expect.
- On sites like ArtStation and deviantart, being active in the community can help too. Not in the sense of 'please check out my work' but just being around.
- Taking on requests can help too. For example; if you were to make book-covers for those sites where you can publish your own stories and make sure you are credited by the writer, that too can help and they might recommend you to others.