I've always had trouble finding somewhere to sell my art, I don't have a problem when people find out I draw/paint, then they always ask for something custom, but say online for example, I don't even know how to go about finding an outlet.
I'm already on deviantart and ebay, etsy didn't work out for me either and pinterest. The only way I think I can really do anything with it is for it to be face to face and I work 2 jobs so I'm at a loss.
Have you tried Etsy. com? That could be a good place to start. When it comes to people asking for custom work, you're not doing yourself any favors by not accepting commissions, unless you have a good reason not to accept them. A lot of freelancers make their money by doing commissions; that's what many of my fellow artists do, depending on what medium they work in.
Honestly, you might get better answers asking this on an artists' forum. You could also subscribe to artist's magazines, like Creative Bloq, which is free. They offer insights on how to market oneself too. And maybe look up interviews and such by successful artists as well.
Lol, the business-side of being an artist... Takes a lot of time. Plant your seeds widely. It's pretty important to let yourself be known. I am not at home in the fine arts, but i think it's a plus that your artvorm is visual, because you can easily make a website, or a visual businesscard, instagram, public facebook or a blog or something. Invest time in exposure of your art, because that's the only way people will know you exist.