There is a lot of posts out there about finding good and relevant keywords for your pages. Basically your method all depends upon what your purpose for the page is. Some keywords are highly converting such as “buy underware now”, but the traffic to such a keyword might not be that high. So, if you are looking for traffic, use another word that you think you might receive better traffic ratings for.
Post about Keyword Research
In this post I will not go on and on about different methods as there are so many good posts out there. Finding relevant keywords is really the art of SEO.