I also thought of naughty things :p

3.6 is okay, nothing to write home about. You should be more concerned about your grades in the context of your future and getting into college as opposed to how it will affect getting into a sorority.

Along with a strong GPA, make sure your resume is filled with extra cirricular activities, leadership positions, philanthropy work, etc. Not only will that help with sorority recruitment, more importantly it will help you get into the college of your choice.