One thing I learned is that cost denotes value. Discount too much, and you run the risk of looking like an amateur hour organization.
Now I'm basing a lot of what I learned from theater marketing books - like this one. Communication is great, continuous communication is better. Get an email list going and maintain it. Make it someone's job to regularly communicate with emails, Facebook, etc., because you need to retain people. Fall off on posting a little too long, and you lose people and need to rebuild.
(I design book jackets and have a degree in Illustration, so) In regards to your flyers: shell out a couple extra bucks to ask a friend who knows design to make flyers for you. Yours scream "I was made by someone who doesn't know what they're doing in Microsoft Word!" Instead, think about your image, your brand (YEAH, your BRAND, fuck it, you need to) and what you want people to think about you. What's the "personality" of your classes? Now start choosing images from there.