I think preparing your daughters for rush is for the best. I am not sure about conversation tips etc. But a long, long time ago... LOL. I went through rush at North Texas, which was highly competitive. I spent the whole summer memorizing the rush brochure, buying the perfect outfits, I was so excited. However, none of my family members were greek so I had no idea about reccomendations. I tried to find a panhellenic for my city, but there wasn't one listed in the phone book. So I assumed it must not be a big deal. (Yes, this was before the internet was widely accessable). I went through as a sophmore with no recs.

I was cut really harshly the first day. I was asked back to some really great groups, but did not receive a bid from any of them. To UNT's credit all of their groups were strong at the time, and there were quite a few girls that didn't even make it to the pref parties. But at the time I didn't know why I was cut or why some girls just didn't get bids. I didn't understand quota, and had no idea that COB was an option. I know I don't want my daughter to be so dis-illusioned.
After I joined AGD I realized that some schools have so many new faces they have to cut the best way they can. And I was told during UNT rush that sophmores really had it hard that year. (I don't think there were any Juniors or Seniors)
Texas*Princess I remember seeing all the cars decorated outside of Maple Hall where all the sorority members resided at the time. It was a great show of panhellenic pride.
I plan to prepare my daughter (fifteen years from now!). Make sure she has recs, good photos, etc. And make sure that she knows that if she gets cut, sometimes it is really not personal. And to let her know no matter what, it works out for the best.
Because it really did work out for the best!!!
Greek Chat is a great tool for pnm's. I am so glad that, if the pnm is really dedicated, that the answers are out there.