The field of search engine optimization is a constantly evolving industry with important changes being made almost daily.

In the beginning, search engine optimizers focused on one thing only: rankings. Tracking of actual sales or conversion rates was almost unheard of.

If a person clicks on a link from a search engine, will they find something of interest which makes them click your navigation to see more or will they leave immediately?

You have to think about how search engine’s index your site. They don’t just take your index (home page) and point to it – nope, they gather all your links to different pages on your site and list each one.

Keywords
Know what you want to be found for. You should know the top two or three terms that are most important to your Web site and have incorporated them into a 25-word description that doesn’t use marketing hype, which can then be submitted to human powered directories. You should also know a list of the top 10 to 100 terms you’d like to be found for and ensure that you have pages within your Web site with good, solid content for these terms to please the crawlers.
(Danny Sullivan of Search Engine Watch)