There are two ways to get listed. The free way, which is not guaranteed and the expensive way, which is guaranteed.

The free way consists mainly of optimizing your site, along with regular networking, creating an opt-in e-mail list for your clients to send them announcements or a newsletter of the same kind, and putting your domain name in your e-mail signature and printed materials.

The expensive way consists of optimizing your site and then hiring a company like overture to put your link in search engine listings.

How Come My Sites Not On Top Yet?
Even after doing all of this, you can only be on top for a certain search phrase or collection of keywords. So when doing all of this you need to think carefully about who your clients are and what they might be typing to find you. Do some user research, ask your friends and family, sit down and think like a user would. What would you search for if you were looking for you? Once you have all of this data compiled, come up with a general search phrase and some keywords to go with it. Then optimize the site for that phrase and keywords.

The best results you may get is three top listings for similar phrases. That is a success, especially for not paying a third party to list you.

When your site gets a high ranking, it is not guaranteed to stay there when going the free route. It takes work to keep your position. Please see Keeping Your Site Fresh and How Search Engines Work for more information.