Based upon what you observe, make changes. Using trickery to get your pages to show up under search terms that really have nothing to do with your site only irritates the surfer. It can also get you banned from the search engines. First you have to decide what your site is about. For example my site is about internet marketing, but lately I have focused on promoting other sites and helping promote other ezines.
Internet marketing is a very broad topic.
So is website promotion or ezine promotion. Still, this is what I decided my site was about. Secondly - choose good keyword phrases. Most people do not search using a single keyword. They use phrases to get a more focused search.