All of the above answers are great. I prefer joining a networking business group and promote my business. These groups can generate many leads for you and it’s always great to have that as an option. You might also want to try one of the daily sites (like Groupon for example). It’s free advertising for you (actually you get paid to advertise) and you can reach a very large amount of potential clients out there. I have done it in the past and it was a great way to expose my business and myself to new clients.
If you have a car you can put your logo and web site on it, so when you drive around people can see and learn about you and your business.