Here are a few things that worked for me:
Facebook group: I just started a group and invited a select group of ladies I had previously chatted with about it. I made the group closed but open (can't think of the correct term). Basically it showed up in searches but they had to request to join it. That way I could speak with each person and explain what exactly was happening.
Wearing pins, 'nalia whenever you can/appropriate: I drummed up most of my interest by wearing my letter pin to other group meetings. It was inevitable that someone would ask me about it, thus giving me a chance to chat about OPA.
Advertising it on my own profile: I listed it as an interest/group. Posted pictures of service projects, etc. I always got questions about it.
I hope this helps!
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ΣΓΡ “The only way to go”
ΩΦΑ “symbol of our friendship always”
The greatest way to combat chaos is with competence