There's lots of good advice here, especially the part about keeping an open mind.
I like the idea of taking notes between parties... but never, ever, let an active sister see you doing it. Make a note of names and what you talked about. That way, when you go back for later rounds, you will remember that you already told Susie all about your summer vacation, so you should talk to Jane about something different.
Try to keep the energy going, even if you have a full day of parties. Try to be just as upbeat and energetic at your last party of the day as at your first. The sisters are just as tired as you are, if not more so.
This should go without saying, but - leave cell phones, pagers, palm pilots, etc. behind. Leave your watch behind, too, unless you have a legitimate reason for needing it - in which case, stick it in your pocket so you're not glancing at it during a party.
Avoid discussing other sororities at all costs. Avoid discussing men and fraternities, except in general terms. Never say anything negative about any person or group.
If you don't have too many sororities to go to on a given day, memorize some basic facts about each house - colors, flower, philanthropy, etc.
Before rush, make up a list of questions to ask at every house - questions about academics and philanthropy are always good. That way, when a sister asks the dreaded "Do you have any questions I can answer for you about XYZ?" you have something to respond with.
Last but certainly not least, relax, have fun, and SMILE
