Google looks at three major things- Meta Tags/data (Including the 3-4 sentence site description), Titles and Content of the site. In their swizzeling of sites, they track the usefulness of sites by their users. The more relevent the site is to users, the higher it will get ranked.
Another item that search engines look at is how often you update the site too. A site that is updated regularly will also carry a higher relevence because the data on the site is "newer". I would also suggest you consider placing a "bots" file into your site structure. Many of the bots that comb the internet,culling information for the various search engines prefer a bot page rather than going through the entire site. There is a lot of free information available online about this and how you should structure the page.
If you want to look at Meta data, go to:
http://www.elementssalon.biz and take a look. This is a web site that I made for the day spa that my wife and I own. There's a flash greeting, but you can click through it. Once you get a regular page up, you can go to "VIEW" on your web browser, and select "SOURCE". This is give you the source code for the web page you're viewing. Within that text, you'll see an html tag that has a "<" to start it and then the word "meta" (There should be two of them, actually... a description, which is what you read on the search engine description of the page and then a keyword section that places words that people use in search engines to look for your services...) then a closing ">". You can literally copy and paste mine if you'd like and simply change the wording. Make sure you place the tag in the same structural location (The head, I think...) so that it's valid and will be read.
On this site, we were, at one time, number 4 on the Google ranking for salons as a general search. We have fallen, I'm sure, because I haven't touched the site in months.
Anyway, hope this helps you out.