Agency contacts are a huge part of getting regular work, especially when starting out as a freelancer.

Sites like iFreelance.com & eLance.com offer freelancers the ability to bid on projects. I found that when I was starting out, I bid on 5 or 6 jobs per week and the ones that came through kept me busier than I needed to be. Also, many times a job you bid on will turn into a regular customer, and agencies often put up jobs on such sites without revealing themselves right away.