The main promotion tool I use is my own website http://www.albruna.nl/ and the portfolio http://www.albruna.nl/portfolio.html.
Another promotion tool are my business cards I give to everyone. Long ago, I learned that it does not matter to whom you give your business card. It might be to someone who has no interest in websites or who has a vague interest but will never want to have one designed. It is still possible they know someone who does. Business cards are cheap so give them away to everyone!
The use of brochures is also a promotional tool I use. There are many potential clients who you will never reach, so why not send them a brochure and tell them what you can do for them. No need to limit yourself to people who have no website, there are plenty of sites that could do with a design update.
Obviously social media also takes up a large part of my promotion. I am a huge fan of Twitter and use my account http://twitter.com/albruna_nl a lot and a while ago I opened a Facebook account http://www.facebook.com/albruna.nl which I am currently getting to grips with :-).
Last but certainly not least!
One of the major promotional tools is word of mouth. When you create something beautiful, user-friendly and professional and give great service, people will recommend you to others!