I went through a little exercise yesterday while trying to find a great domain name for a side project. Nothing too scientific, but the whole process reminded me of how hard it is to settle on a single domain for a brand. Do you go with relevant keywords? Throw caution to the wind and select something obscure? Use a new generic top-level domain (gTLD)?
For this example, let's go through the naming process for an imaginary tech review blog.
To start, it's always good to put down the obvious. And here, the obvious choice is to use some combination of the words "tech" and "reviews." Common phrases come with ferocious competition though, and a quick search for "techreview" proves that by eliminating popular TLDs like .com, .co, .org and even .club. But there are a number of great TLDs available, like .expert (techreview.expert) and .io (techreview.io). Do some research though on the other sites with the same name to make sure you're not competing against someone doing the same exact thing. You don't want that sort of competition in your life, and you certainly don't want to be thought of as a copycat.
Taking simplicity one step further, you can also just search for root words, like "tech." That particular word turned out to be a dud here (unless you're specifically targeting tech for cruises or futbol), but it never hurts to try.
The next step is to look for related terms, like "wire" and "electronic." Think of similar sites like thewirecutter.com, engadget.com and wired.com, then run through a list of 10-20 words (or more) and mix and match and jumble phrases until you get something you like. A lot of people will also tell you to stick with a .com here, but I think that's a conservative way to look at naming. There's a whole world of relevant TLDs that can be combined with short words to create concise, memorable domains, and you'd be severely limited by not considering one.
Speaking of thewirecutter.com, using "the" in front of a name can be a good way to show importance (not just one of the best, you're the best), but know that you're always going to have people confused as to whether the "the" is in the domain or not. In this case, The Wirecutter uses thewirecutter.com as their primary domain, but also uses wirecutter.com as a secondary forward, just to eliminate confusion. If you decide to go with a "the," you really should protect yourself by having both domains.
The last thing to look for when dealing with generic phrases are possible domain hacks. After the launch of the new gTLDs, domains hacks fell a bit out of favor, but if you think you can pull one off, go for it. For the uninitiated, a domain hack is a domain that uses the TLD as part of a word. For example, instead of naming a site about Trekkies, trekkies.com, you could name it trekki.es. So instead of using .com, you end the natural word with the .es country code TLD (ccTLD)) at the end. Domain hacks are clever, but beware the verbalization problem. It's easy to tell someone a name ending with .com or .expert, but verbalizing "trekki (that's two k's and ends with an I) dot e s" could be unnecessarily complex.
So once you've exhausted the all the generic phrases, relevant keyword jumbles and domain hacks you can think of, my suggestion is to come up with some words or phrases that sum up yourself or your product. Think daringfireball.com, John Gruber's blog that rifles off educated opinions like a daring fireball... or something like that. Or perhaps theverge.com, covering "the culture of now." The phrase "daring fireball" especially has little to do with its subject matter, but John Gruber's continued dedication to his blog has made it a success.
And that brings me to the most important tip of all. At the end of the day, what's important is not your domain name, it's the content that lives on it. If it's good enough for long enough, it'll get read no matter what your domain is. If it's not, it won't. Just take the time to find a name you're happy with that doesn't paint you into a corner (i.e., don't limit yourself to a domain with the word iPhone if you might eventually review Android phones) and go with it. Every idea is a good idea once you make it so.