Marketing Of Your Training / Seminars

I am looking for input on marketing of my training services. Specifically, how do you get the word out that you are putting on a training class?

I have found a few PC classroom companies that will do the registration, certificates and other administrative work but I need to find someone that will do the up front job of marketing and filling the seats.

How do you independent trainers get the job done?

Thanks for any and all input.

Tim