I do want to tell you to be careful using fraternites too much. I don't believe we are actually allowed to have men at our rush events. So please don't violate NPC/AST rules. I am always cautious about having men be the reason women join. We are a women's organization and those bonds need to exist independently of men.
However, if you have active fraternities where you know the brothers. Meet their girlfriends. These women are not anti-greek, maybe luke warm on the whole thing, but not dead set against it because they ARE dating a greek. Get to know these women. If you know the men well, get them to put some good words in for you. Do a co-philanthropy and get them to bring their girlfriends.
Look at the president of all the campus clubs. Get them involved. Orientation leaders, RAs, sports teams. We had some good numbers because we had one sister on the soccer team. Recruit a whole team at once, it brings the bond they have already, and expands it. The Sig Chi chapter at my alma mater saved their charter with the baseball team.
I wish you luck, keep talking to us and we'll help ya out. PsychTau would be good for you to contact. She has some great ideas and is a Greek Advisor in VA.
Tau Love