If you know how to get websites to page one, why are you not marketing that fact to potential clients and consumers or would-be domain purchasers? Trying to get a keyword driven domain to rank high and sell it off for a profit isn't a good investment, either time wise or for the long-term success of your company. Instead, use sites that you have already ranked high as an example of how awesome you are and sign them up for a monthly fee, rather than trying to sell them a "make money now" domain.
Also, Sedo.com, makes millions a week selling domains,even in the past week! If you want to sell here, I would probably use a paid category or featured listings, one of my category listings, got 44 views in just 1 week but still waiting for a sale this month, hopefully. I would not really on this as a business, unless you add web development to it, and also, be sure to check that you are making a good profit, say within 6 months!
Yes! Selling domain is an emerging trade and no wonder if it can develop into an exchange. www.DomainX.org has been initiated with this view. There are some good ideas in the comments regarding which names to buy and how to grow their value. However one must not forget that it also involves a recurring cost (annual renewal) and keeping many of them might become difficult if you are not really selling at least a few to cover it. Enjoy free listing at DomainX.org.
Park the domain with a domain parking service. Since you may not have content to put on the site, a parking service puts up a dummy page with ads. When people visit and click on the ads, that's money for you. This method works best with popular keyword domains that get lots of traffic. In most cases, you will not have control over what ads appear on your domains.
They see a domain’s price tag and they can instantly tell whether it’s under or overvalued. This is probably the most important skill one should have in this industry. Neil Patel has an interesting related quote: “The most important thing to remember when buying sites is that you always make money on the buy, never the sell.” In order to successfully do this, you must be able to spot undervalued domains. This is what will ultimately translate for you into a handsome profit margin when you get the opportunity to resell the domain for its “real value”.