There are a number of services available that can help you with selecting the most appropriate keywords for your site. These services base their suggestions on results from actual search queries. Google provides a great keyword tool (https://adwords.google.com/select/KeywordToolExternal) to assist with keyword selection. Wordtracker (http://www.wordtracker.com) is another example of such a service.
Keyword research tools can help meet your current needs, whether you’re looking for a place to start, are plum out of ideas, or simply feel like you’re missing something. See the Resources section of my Web site at http://www.SusanSweeney.com for a list of keyword research tools.