First, each page should target specific keywords. And, like Jazzee said, put those keywords in H1 tags and in the page titles.
You can use WordTracker or Overture to see which keywords people are using.
http://inventory.overture.com/d/sear...ry/suggestion/
Also, look in your webstats to see what search terms people use. If you post some of those here, I can give you more specific advice.
