A direct-mail marketing campaign can be used as a kind of portfolio review. Develop a mailing list of real people at organizations you'd like to work for (websites, annual reports, and basic online searches should give you plenty of contact information), create a schedule, and mail things out on a regular basis. Realistically, prospective clients will need to see several pieces from you before you'll even register on their radar. And don't expect them to just pick up the phone and call you. You have to be brave enough to do follow-up phone calls and ask for a face-to-face meeting.
Make sure your mailers don't showcase only the work you've done, but are also inventive, arresting, interesting, and creative pieces themselves. In this day of faceless, high-tech communication, a well-conceived and executed piece of mail may actually stand out more than you expect. Which brings us to another important point: Make sure your mailer goes to a real person, with the right title, who is in a decision-making position, and actually still works at the organization you're targeting. Be sure to spell his or her name right. Make sure you know something about what the person or company does when you call. If you get a meeting, spend most of the time asking about the company's needs, not telling them how great and accomplished you are. Then follow-up with a personal note that tells them what you learned and how you think you might be able to help.