You could start a blog and put examples on it. Blogger.com is free and can be used for commercial uses.
You could self host a Word press blog too for just a few dollars a year.
Once you have blog,you can put it in your signature on forums or post it in profiles of yourself on social networks.
You could also join sites like elance.com. That isn't free but you can bid on some projects with free sign up. I think bidding on more lucrative projects runs about $75/quarter and you can drop the membership if you get enough work.
I think having a blog or website is probably essential to getting the word out on your business. It would allow you to connect with potential clients anyplace in the world.
You might consider doing some projects for free for charities too. That can lead to other work and it gives you samples of your work and references.
