UCLAlumna is absolutely right. Join the sorority that feels like home and only join when you're ready. I waited until after my first quarter so that I could get a feel for my schedule and classes. UCLA is a quarter system so 2 weeks in and you're already 5 weeks behind. I ended up joining Kappa Delta and made friends that I will have forever. I've been best friends with them for 7 years now. Friends by chance, sisters by choice. These are girls who share some of the most important memories of my life. I've never regretted my decision to join a sorority and encourage every young woman to try it. When you're far from home, it's nice to have a support system to lean on.
Sorority "rankings" change every year it seems. I've never been a fan of the ranking system and believe me, once you reach your 3rd year it won't even matter. What matters are the young women who laugh with you and cry for you. The girls who will see you at worst...and love you anyway. Good luck and enjoy!