There are many different ways to sell your domain names online. A listing service is a great option for domain owners with large portfolios since it is difficult to promote hundreds or thousands of domain names to private buyers or through domaining forums.
In this video I discuss the basics of creating a good listings for your domains so that you are actively promoting your domains for sale. Many new domainers think that by simply putting their domain up for sale at a listing service means they are actively try to sell the domain. Without actively promoting your domain name and showing a buyer the value it offers them you are not promoting your domain and could miss-out on potential buyers.