Great ideas from mar. One thing I did that worked well was to offer a free "week-end warrior" ground school. The students had to buy a written test book, plotter, E6B, flight plans and had to pay for the actual written. I ran an add in the newspaper and had the students enrolled a week in advance. I told them that they needed to go through all of the wx, airspace and FAR Q's in the book at least two times before the class. I would go through flight planning, navigation and help with regs and airspace in class. They also had to make at least an 80% on a practice written I made in order to get the sign-off.
One more thing that brought out some students. I put out boxs around Mothers day and Fathers day to give Mom and Dad an introduction flight for there "special" day. It worked well. Good luck, I hope this helps.