I recently started an alumnae association with a sister and researched groups from accross the nation.
First, what is your target audience? Do you want all sisters, recent grads, a more established group of women? This plays a huge role in how to structure your group. As an example, our group is not that structured in terms of "meetings." We are geared for young professionals who live in and around the Atlanta area so we have get togethers once a month after work to relax, maybe have a drink, go to jazz clubs, etc. If you want a group with sister's who are now mom's then you may want to have events where kids can join them. It just depends on your target audience. If you have a large group of sisters in your area and you want to target them all, then you will need to program for all their needs over the course of a few months to attract everyone.
If you look at Sigma Kappa...they have a pretty cool plan that we looked. We also found an association that was similar to what we wanted and contacted their president in New York. Here are a couple of examples. Also, a cool website that's modern and hip tends to draw in people too.
http://www.nycalphaxidelta.org/
http://januarydawnphotography.com/azd/
Good luck!!!
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