I assume you know the latest info about keywords. After that, Google looks for links to your site. A top site in a competitive category can have thousands of quality links, but you can get traffic on a lot less.
Submitting to directories other than Google is a smart idea (google for other things; the biggies are Yahoo and MSN but there are thousands of other directories). Posting on relevant message boards - ones that allow your info in your sig - is surprisingly effective.
It "traditional" (love that, it's only been a year or two) to post a blog that links to your web site. It doubles the amount of info that Google puts into analyzing sites. Update the blog, and the website, every few days.
Also, you can sell your info on ebay (very cheap, ebook) and put into your about-me info the link to your site. It's cool to get paid for attracting traffic. Follow ebay's rules, of course.
Offline public relations can get you a lot of interest, if done right and if you have the right kind of site. Your local paper will print most anything about a "local guy has new business". Find a journalism student to write PR for you as a project.
Good luck.
