I guess I just kind of left it up to them. My oldest was not interested from the get go, he is involved in a sport, and didn't have the time or inclination. My second is loving every minute of greek life. Don't know about my third, he's still in high school, but he can do what he wants.
I think/hope that by the time they get to college, theyv'e been built up enough AND been knocked around enough to know who they are and where they stand socially. Hopefully, they have the confidence to handle rejection, and hopefully, they've been apprised of the realities of rushing.
BUT, I have boys, where rushing is much easier and more laid back, so my perspective is probably very different from a girl-mom. I have to admit, I'd probably be a wreck if I had a daughter rushing
I still think you have to let them find their own way, and help them along if they stumble. But, stumbling is how you gain maturity. I don't think you're doing your children any favors by trying to shield them from life's bumps and bruises.
Just my 2 cents