A good majority of web developers view the domain flipping industry with disdain as they face a hard time finding the right domain names for their own development projects. Domain flipping is also looked down upon by corporate and business entities who register multiple domains related to their trademarks or business names. Actually, it is these people who’re the real domain name squatters!
All very relevant points for anyone wanting to sell a domain name. Sometimes it is the basic points that we need to be reminded of in a transaction like this. What is the potential of selling a .com domain that has a relevant search term to a particular industry, but hasn’t been used on a website yet? So it is a good search term but no current traffic.
The easiest and least time consuming option is to 301 redirect the old domain to your existing site. This tactic obviously works best if both sites are in the same sector and are targeting the same keywords; otherwise, if you have a pet supply site and you buy an old Texas Hold 'Em poker site, a redirect probably might raise some eyebrows among the search engines. If, however, your site is brandnamepets.com and you buy onlinepetsupply.com and 301 redirect the domain over, you're inheriting a lot of topical and appropriate links.
Many non-savvy internet users may not even be aware of the existence of other extensions. That said, because there are many new extensions popping up every now and then, you can often find amazing one word and 3-letter domain names with these new extensions that are otherwise almost impossible to find unregistered in the .com world. Additionally, these new extensions are becoming more and more familiar to users every day, hence it's almost certain that their value will continue to increase as time passes and wider adoption manifests. 

For the following TLDs you can now find a expired/deleted domain list. .gi, .gl, .gy, .hn, .ht, .ky, .mu, .om, .pf, .qa, .rw, .sb, .sm, .sn, .st, .sx, .tc, .tl, .ug, .uy They also show up in the Deleted Domains (last 7 days) list and in the Domain Name Search, however they are not in the pending delete list! I do not have a working droplist for them yet, so that is why they are not released in the pending delete list yet.
These should be more than enough to get your domain in front of tons of potential buyers. If you did a good job picking an awesome domain, you should have no problem (eventually) selling it. You need to be very patient as it could take months or even more to land a decent deal. A lot of domainers sit on domains for years before actually selling them. This is why it’s best not to obsess over a domain and simply move on with buying and listing others (or going back to your day job if this is a side gig) once you've listed the initial one.

The practice of exploiting misspelled variants of popular websites for personal gain is known as typosquatting. Users who incorrectly enter URLs into a browser’s search bar may be getting more than what they’ve bargained for and end up on a squatted domain. We’ll show you how typosquatters exploit the simple workaday mistakes of internet users and how website operators and their visitors can...
Many top-level domains, or TLDs, out there have the potential of being sold at top dollar rates. Gone are the days when domain names with ‘.COM’, ‘.ORG’ and ‘.NET’ were known as top-level domains. Newer domain names with ‘.US’ and ‘.IO’ are also worth their weight in gold. All you have to do is conduct thorough research in order to find all the good domain names you can park.
When I first started online, I'd register domains that I thought I could develop and sell at a later time. After learning my way around the cloud, I realized many of the domains I'd registered are pretty much useless, or so I thought, and I let them expire. Come to find out several of these domains have been picked up by parking sites and are being offered for sale for thousands of dollars! Now I'm not saying they're actually selling for the asking price, but I learned my lesson. I never allow a domain name to expire. I add content to it, backlinks, some AdSense and try to sell it for something.
Wait for people to contact me: When I bought my two domains, I didn’t pay the extra $12 for Domain Privacy, learn about Domain Privacy here, so anyone can look up the owner of IHateCold(.com) and ReallyFunnyJoke(.com) in the ICANN WHOIS Database. It can tell you whoever owns any website unless that domain owner pays for domain privacy. So if someone was really interested in any of my websites, they could look me up and shoot me an email about their interest.
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”.