Heading tags (h1, h2, h3, and so on) are a great opportunity. It's where the expert optimizers begin to distinguish themselves from the amateurs. Despite the reliability and soundness of heading tags as tools for optimization, they are often not employed by webmasters. With optimization akin to a race where you need do only a "little bit more" than the competition, sometimes heading tags will provide that "little bit more" you need to rise above the fray.
Heading tags were originally intended to operate like newspaper headlines and subheadings. They were, and are, taxonomical clues to both the topic and structure of a web page As such, they are great food for search engines, and great signposts for you to send to search engines. Curiously, the use of heading tags diminished as the web grew out of infancy. The rise of CSS as a web technology near the turn of the new millennium let web designers format text with such new flexibility and power that many no longer bothered...