In this article, Danny Sullivan does a great job of explaining the various elements of Search Engine Optimization. What it basically breaks down into is, Content and Links: what you have to say, and how much attention other people are paying to it. Those are things that can’t be “gamed,” the way that people thought they could do with meta tags, or paid for, the way some of the huckster “get ranked higher in search engines” ads try to tell you.
The moral of the story? Have something relevant to say, and have a system for spreading the word!