Hi oceanphi
The way our chapter used to do it was pretty similar to the way oceanphi just explained. We just changed it this semester.
Basically, the point system is something new. We used to just do it that everyone put in their top 3 choices for bigs and littles and that the NM Educator tried to match it up as best as possible. I'm not a big fan of the new point system because I think that the new girls should have the advantage. In a small chapter, it's easy to figure out who you fit in well with and who you look up to as a role model. I know I would have been absolutely heart-broken if I hadn't had my first choice for big sister. My second choice would have been our NM Educator, and we know that that's not supposed to happen.
My big sister really emphasized how special the big/little sister bond is, which is why I think this way. I want the girl to really want me for her big sis, so that she doesn't feel like she was just assigned some random girl.