While i use Efty and Undeveloped, I think to be serious in domain name sales it is almost essential to have your own website as well. I have had one for about a year now, although I continue to expand and embellish it. Here is the link, and I welcome any comments and suggestions.
https://NamesThat.win/
I have moved away from using my site to directly sell domain names, however, and as you will see I encourage through links someone wanting to purchase to go to either a NC Marketplace listing or Undeveloped listing. I am happy to pay their commission for the ease and security of them handling the actual sale and transfer of the name.
I view my site as having the role of promoting the name, rather than direct selling. The most important parts of my site are a full list of all names I have, arranged alphabetically, and a thematic catalogue that for example lists the science, design, etc. names all in one place. They are linked from my main page, but you can also go directly from these links;
Catalog:
https://NamesThat.win/categories/catalog.html
Full List:
https://NamesThat.win/domains.html
I have a few Adsense ads on my pages. They only generate a tiny amount of revenue, so trying to decide whether to keep them or not, whether they turn people off.
I periodically check and find that in the niches that i specialize in, at least in Canada, I have achieved high ratings on Google search - e.g. if you search "science domain names" I am the third listing.
I have plans of increasing the amount of general content in the form of guides on various brand/name related topics that would be of value to startup or business owners in general, but have only a tiny amount of that yet.
Thanks for any feedback, and I encourage the OP to set up a website.