I find when selling Art the problem I ran across is pricing the artwork. At most since my area is art poor in the state of Texas or at least far west. So it comes down to explaining the person the artwork is worth this by showing the cost of the framing and the media used to create it. Most people are insulted saying that they can get for less somewhere else. The second part is exposure. Online sites like Ebay, etsy, Saatchi are good. I ran into problems using them. Saatchi has W-2 forms for the IRS. Etsy has a limit how much you can sell but the problem it is usually for less than certain amount in dollars. Ebay has the $5000 amount per month.
In selling Art is all about the Location. People here offer $10 for a work that I put in $100 of dollars in work and time. My response is usually are you joking.