Here are some things that I recommend:
1) Make sure your site is listed with all of the popular search engines
2) Make sure your site is listed with all of the hosting search engines. You can go to Lycos to get a complete listing.
3) Stay and monitor the forums. Don't try to get clients out of these forums, use the forums to get your name out there.
4) Banner advertising can be effective and there are several sites where you can advertise for less than $200 per month.
5) Monitor the USENET forums.
6) Word of mouth your business
7) Take out a classified add in your local newspaper.
These are just a few that I can think of. Good luck with your new business.