Keywords are important on many levels both on and off the site itself (See: Anchor Text, Title Tag, & Onsite Optimization). In fact, even choosing an URL that has your primary keywords in it is beneficial to the cause of SEO. In that regard, in ways like a book sitting on a shelf, while the Title-Tag serves like the front cover, the URL works like the binding cover. If both the Title-Tag and the URL match on the most important keyword phrasing on your site then your site is going with the grain of search. Don’t be alarmed if your URL does not have a primary keyword in it though as such a deficiency can easily be overcome using other optimization techniques.

When picking keywords it is best not to pick a single word as a keyword because a single word is not searchable. Beyond that, according to a report covered by Search Engine Watch:

 “a single word accounts for [only] 15.2 percent of queries,” while “internet users who type two words for a search engine query account for 31.9 percent of searches, and three-word phrases are used for 27 percent of searches, and four words are used for 14.8 percent of searches.”

Almost always I advice clients to pick 3 word key-phrases relevant to their business while simultaneously having two word key-phrases as a possible future goal. Newer websites are better opting for 3 word phrases until they become more trusted and gain authority.   

A valuable tool to aid in keyword discovery can be found here http://tools.seobook.com/general/keyword/ 

Here at Vital SEO Marketing, if you seek our services we will evaluate your keyword choosing and advice on potential key-phrase adjustments.