Hi Donna,
Good question! I'll be interested to hear what others do, too. I do quite a bit of online marketing through local listservs, websites, etc. I rarely do print advertising; I usually have some flyers to hand out to individuals I talk to and leave in a few key places, but I don't do a blast all over town. The best success I've found is based on teaching location. For example, I'm currently teaching at a community center, and while most of my students didn't find out about the class directly from the center, it has sent me a fair number of students and establishes the vibe that this is different from most yoga classes. As you mentioned, word of mouth is definitely helpful, too; for me that grew slowly, but I've seen the benefits over time.
I think quite a bit depends on how people usually spread the word in your town. For instance, where I live, the neighborhood where I teach (and live) has a listserv that is a good way to share information. Where I lived before didn't have that, but most everyone read the local paper because it was a smaller town, so advertising on their site was helpful.
Hope this helps! I'll look forward to hearing other ideas. Have a great day!
Best,
Anna