First thing to do is make sure all your tags that search engines check on your website are very descriptive and as short as possible while still covering all aspects of your website. Believe it or not, if you have a one page description, the search engine will take lower priority of it in ranking the website.
Second, make sure you have tons of links to your website from other websites, that helps tremendously. When I ran my website, it was based around topsite lists, and so naturally everyone had to link to my website, with over 10 lists and more than 500 members in each, I had quite a few links, ranked #1 under certain search words at google
Also, if your website is based around one single topic, make sure in the tags they check, that you have used that word plenty of times.