I've owned and operated several sites over the past few years and this is always the holy grail. You need to build links back to your site from other sites. These are commonly called backlinks.

You also need to have constantly changing and/or updating content. This tells the search engines (Yahoo, MSN and Google) that your site is dynamic and being cared for my a dedicated webmaster. If your content rarely or never changes, the search engines have no reason to come back.

Lastly, I recommend that you spend a ton of time in forums.digitalpoint.com. They helped me out more than any other site.