The new member handbook says that you should have the girls list their top 3 choices and the reasons they pick that person as their big sister. Seeing problems that we have had with big/little matching in the past the reasons were very helpful! It helped us to see what matches were the most beneficial to eachother. If you havent had your new member class write their reasons out before it may help you put a new spin on your matching process.
Examples of good reasons were "she has helped me memorize the creed and balance ZTA and school work"
as opposed to "we have fun together"
Its important to stress the point that a big sister is a mentor and not a best friend.
Hope that helped
ZL