First get in touch with many people of your interest field and share your thoughts with them. Write blogs and articles on your profile and attract people for giving reviews. Make some interesting video as it can attract people more.
create a facebook fan page of your site suggest it your friends, family and colleagues, post your facebook page link on other relevant pages to promote it, create a twitter account and link it to your facebook fan page hence your facebook updates will automatically tweet on twitter too :)
Nancy: this should have gone into a new thread. this question also is repeated every few days, which means you'll already find a lot of threads where this question is answered. you may want to go through those first.
In social media you need to focus on relationships. Kindly do not do heavy direct marketing. People will get turned off. I do income taxes for locals in a town of fifteen though. I use my Facebook Business page to share fun images with locals.