Probably nothing—and if you are doing something wrong, it'll probably take you at least a few months to figure out what! The fact is that, in today's intensely competitive marketplace, it's virtually impossible to launch a new site and have it dominate search results within a few days, a few weeks, or even a few months. Why?
- You have plenty of competition, and they have had a substantial head start (that law firm down the block may have had a web presence for 10 years!)
- Google wants to wait and see how you perform according to its “quality” algorithms, and how “sticky” your site is when visitors land on it. That takes weeks to establish.
- You may have targeted an extremely competitive search term (say, “New York personal injury lawyer”), and you'll have to lower your sights to something more reasonable.
- Adding new content on a regular basis is one way to improve your site's rank, and that's a process that takes a lot of time and effort.
Of course, it's possible that you did do something wrong when launching your site—so there's no harm in checking and re-checking your SEO practices (did you “overstuff” key phrases on each page? Is each page of your site distinctive and original, or did you use the “cookie-cutter” approach whereby each article is substantially the same, but targeted to a different geographic area or key phrase?)