A desirable domain name is short, sweet and memorable. The most valuable domains are often one or two dictionary words which are related to specific products or services. Such domains are usually entitled "dictionary generic domains" and are highly sought after by domain buyers. Domains such as "mobilephones.com" or "computers.com" are obviously going to be extremely valuable, but are also going to be likely to be registered. One thing you can do is seek to register these same domain names in TLDs (top level domains) other than the extremely popular .com (such as .co.uk, .net, .mobi, .info and .org).

Another thing is to try to be a bit creative and think of a "brandable" domain. This could be a number of words linked together which sound good and are memorable, but may not necessarily describe a product or service directly. This domain name (wonderdomain.com) is an example of such a domain. Brandable domains can also be completely made up words, as long as they are pronounceable and catchy (e.g. circutec.com) or very short ones (e.g. pimo.com).

A good starting point is to look at domain name forums such as those contained in my "what to do with your domains" article to see the kind of things people are after. Don't go crazy and start registering hundreds of domains with the aim of trying to sell them on such forums, however, as they may not be quite what the buyer is after. Think of this is a tool in your arsenal, not a path to which you are bound.

Also bear in mind that developing a website with original content, so that it attracts visitors, is likely to make your domain far more desirable to a prospective buyer. A great (and free) idea with what to do with your domain in contained in my "what to do with your domains" article.