Being part of a school that has little money to do all they need for advertisement... I will tell you what can help, if you haven't tried them already.
Offer a buddy system... especially to the younger students. Have each one bring in a friend, or two, or three to take class with them for free... that buddy will get 30 days free. If they are at every possible class, and show the enthusiasm, you'll probably get'em to sign up. Talk with the buddy's parents... get a feel for what they're looking for.
B-Day parties are great. You supply the building, and a free class to all who attend. We usually get at least one new student after doing a party.]
Offer, every 3 months or so, a free self-defense class open to the pubic. BE specific though on each one. Child self-defense (ie. stranger danger) women self-defense (13-15 and up) or men's self-defense (though few men will probably show). Contact the local papers and tell them it is a community event. Chances are that they will post it in the newspaper for free.
And speaking of free advertisements.... every time you have a tournament.. take a picture of those who did well and send it into the paper. More often than not, it will be published. Don't forget to include names of those students and your school, of course.
If you have time, get involved with the local schools (not the other MA schools). This is a little more involved, but well worth it.
We typically contact the school's priciples and let them know we are interested in our students behavior, grades, etc. in class.
Doing this shows the parents that we care. Parents keep us aprised to grades and we have even made their report cards as part of testing requirements. This is to support that they must be mentally strong as well as know the physical aspects of martial arts.
Ask the partents what they would like to see. A questionare is always good feedback. Suggestion box, or the like, where annonymous questions or suggestions can be noted. They will feel more involved and you might even note a problem you didn't even know about. This my not directly get you more students but, it will retain the ones you have. Besides... it takes a thousand compliments to make your image shine but, only one bad one to tarnish it. A happy customer my not tell anyone about your school but, an unhappy customer will tell everybody about it... along with the problems "they" see... even if it isn't really a problem.
Last, and not least.... payments. Only you, or your staff, can help you here. It may sound bad... but, you have to be sure customers are current on dues. Some schools may not have this problem... some may. Either way, you can't afford to allow people to get instruction for no return on the investment.
We had a major problem with this in the past.. its a touchy area. If you flat out say that you can't come back until payment is rendered, you could lose them forever. We found that by bringing up the fact that you will not allow them to test for the next rank until payment is received, people have a tendancy to pay and still come to class.
They worked hard to get the next level. They want that next level. And once they get that next level, they want to learn all they can because its new material and they get excited about it and forget that you asked them for money.
No, its not fool proof. So, you have to be prepared to let a customer go because of payment. If they don't pay you, then you can't afford to keep teaching.
Well... that's my view on it. We have been fairly successful using this. It may all depend on location as well. At any rate.. I wish you the best of luck!