One of the ways I sell domains is by finding clients to buy them buy directly going to a client. I had some print domains that were surplus and one visit to a print trade show and poof I had no print domains in surplus. It depends on the domain, perhaps you want to research like domains and see if those people would be interested? If you have acmehardware.com maybe you want to look at acmestore.com or something to see if they would be intersted in your domain for SEO? When I suggest domains for my client I often suggest domains around my choice also for them to buy as well. Hope that helps!