There's some great advice here.
I second the advice of not just asking the PNMs "so do you have any questions about XYZ?" I got that from
every single sister I talked to at one sorority during FR. I had a few questions I'd thought out ahead of time, but when those ran out, I felt put on the spot to come up with something,
anything, to ask, and it made me very uncomfortable.
Trust your sisters or brothers! Unless there are very few PNMs, you are not going to get the chance to meet them all, and you will have to rely on your sisters' or brothers' judgement.
Practice your conversation skills, especially if you are shy or quiet. Your sisters or brothers can help you there.
Leave your watch at home, so that you're not tempted to check it while talking to a PNM. If you're a girl and you feel naked without your watch, get a pretty bracelet and wear it on that wrist.
Never badmouth anyone. It's ok to say "ABC is the best" but don't follow it up with "and DEF sucks." Be a lady or gentleman.
And relax