you can also ask simple get to know you questions beyond the typical small talk. You can ask them questions about what kind of music they like, what kind of movies they like, what if any intramural sports they participate in, things like that. The sisters are just as hard trying to find common ground and connections with the PNM's just as much as the PNM's are with the sisters. In fact my chapter during rush tries it's best to ask the PNMs questions about their hobbies and interests as much and as soon as they can to try to step out of the same conversations that teh PNMs have experienced at every other chapter they have visited. (and apparently this is starting to work for us as we got more PNMs accepting our invitations for pref than any other chapter on campus, and we got quota plus 3). Other than that, i wouldnt worry too much about "awkward silences" as it may be her first time rushing on the other side as well, so dont always look at that as a bad thing
good luck with rush!!!!!