I also am a member of a local sorority. At the school that I went to my sorority was a part of panhel so we rushed with the NPC sororities during formal and informal recruitment. Rush at my school was not very competitive...it is very hard for us to get girls to sign up for rush and come to events. I think it is because my school was a commuter campus. Back when I rushed (1996) there were ~45 girls signed up for recruitment. The numbers have been going downhill since then.
Over the summer my girls have been busting their butts to get more people interested in Greek Life...guys and girls. We would like to see a bigger Greek system at our school...right now it is probably less than 1%.
Do a search and you will come across a lot of threads related to PR. Promote your sorority and Greek life in general whenever you can!