Choosing the right domain name presents certain challenges. For example, if it's for a bricks and mortar business website do you just use the name of the business, or include keywords to describe it?
Obviously if it's an established business that many people already know about, or will become aware of in a short space of time, then you should just go with the former option. People will search for the name and your site will be at the top of the results, and it will almost certainly draw some natural links from local blogs and websites as well, meaning that any disadvantage from not having keywords in the domain would be quickly overcome.
But if you have a very new and small venture that no one knows about it may well be an idea to use keywords. Say you are an accounting firm in Subiaco. Research might indicate that including the obvious keywords "accountants" and "Subiaco" in the domain name might be a good move. It could draw in a small but high quality flow of traffic very soon. Unless you really built up the business and developed a very strong brand it could work well for a long time, even indefinitely.
That said, I think in most cases the best long term strategy would be to use the business name itself. It's the obvious choice, is easier to remember, and won't ever need to be changed (unless the business name itself is changed, of course).
I've been thinking about building another site lately and so I have been pondering what domain name to give it. This is always a bit tricky because I've got to consider the SEO aspects, but it also has to seem natural and be easy to remember.
This ease of recollection factor is important generally, but it is crucial when it comes to getting word of mouth interest in a website. And that's still definitely worth having, even though people tend to forget it.
For this reason it's always preferable to have a domain name that's fairly short. So two words is good. And three can be fine if each of them isn't too long.
I also think it helps a lot if the title you give to the whole website is an exact match with the domain name -- or at least very close to it. It also helps if it's a "dot com", because that's still the one that most people automatically think of.
And you should try not to use dashes in it if possible. If you are trying to tell someone what it is, these make it sound very awkward. And people always forget where they go, anyway. (I know there is a school of thought that says dashes can be useful for clarification in some cases where words other than those intended can be perceived. By strongly separating them, dashes make Google's job easier. But such cases are rare. And I think the search engine is more than smart enough to figure out what they are now anyway since it will factor in the website's overall content.)
If you do these things you don't even have to meticulously describe the whole domain name when you or other people verbally promote your website. You just say it is called "My Own Site". If they want to have a look they'll string those words together and usually put the "dot com" on the end and know what it is. But even if they don't they'll just search for those words and your website will tend to come up at the top of the results.