Good Thread.
I think the biggest thing is simply making friends and often we forget this.
Don't introduce the sorority in your first or second meeting. Make friends, slowly introduce them to sisters without pushing the sorority aspect, eventually talk about it, but people join people they like, not just the pushy ones. If they say no- well, you still have a new friend.
The chapter I advise has really gotten this into their recruitment strategy and is doing just fabulously.