I've been teaching women's self defense since 1992 and have always struggled to fill classes. Good for you Kevbo - doubling your student base with women is AWESOME! It's so encouraging to hear that women in your community are stepping up and facing the reality that they'd better know if this stuff is going to work against a larger assailant, rather than opting for the Tae-Bo type training. And to have them respond so quickly to your ad shows that they are really ready to be proactive!!

Unfortunately, on the whole we've found that, as much as many women "know" they need self defense training, unless there is a reason (i.e. they are an assault survivor or there is a rapist in their neighborhood or a friend or relative has been assauted, etc.) there is a deep resistance to actually take the step and sign up for class ("I've always wanted to take a class. I know I should, but..."). It's part fear, part denial and part "honest-to-god-I-just-don't-have-the-time" busy lives that prevent many women from taking the step to join a program, so finding an effective way to reach them is like striking gold!
An approach we use to appeal to a wide range of women is to stress in our ads that not only will they learn to physcially defend themselves against a variety of real world crises, but moreover, they will come away with INCREASED CONFIDENCE and AWARENESS and an overall sense of EMPOWERMENT as a result of their training. It's very appealing for a woman to think that her training will not only make her more capable of defending herself against an assault, but she will also be able to be more effective in her everyday dealings with family, friends and co-workers. Broadening the description of the training can make it less threatening to those that might not feel physically able to take a self defense course...and it's certainly not false advertising, either! Once they're in the door (often the hardest part of the training), they quickly come to understand that the physical and mental / emotional aspects of living more safely are intertwined. You really need to have both to truly be ready.
In addition to Kevbo's suggestions, think about making contacts / presentations at women's shelters, health clubs, police stations, even business women's groups / networks can be great, as they are often in need of presenters for luncheons, etc. Don't overlook AARP, as there is a growning need for self defense / personal safety among the elderly and these days there are some seniors that are in fantastic shape. You could have some rockin' classes with these folks!
Finally, in the interest of widening the appeal of your program, another component to consider in women's training (or any training, really) is a realistic verbal boundary setting piece. It requires a male instructor to assume a variety of different characters and interact verbally with the student, allowing her to use her words and body language to deal with the situation (I've talked about it in detail in other threads on this forum). Being able to offer this type of realistic role-playing in addition to solid physical skills provides your students an oppportunity to practice how to control, diffuse and deescalate a potentially dangerous situation before it gets violent. Again, these are skills that she will be able to employ in every aspect of daily life which makes the training that much more useful and appealing!
I look forward to hearing how your program is doing!
Meredith