I rushed as a Sophomore at Auburn University and I am glad I did! Some sororities are more open to Sophomores than others, but you just have to take everything in stride. If you go in it realizing that some may cut you simply for that, then you'll be fine. When I rushed, I tried to use my being a sophomore to an advantage. Since I had observed Greek Life on campus and made Greek friends one year before rushing, I was able to truly say that I wanted to be Greek and enjoy the sisterhood of a sorority. Many sororities found that impressive and as a sign of maturity.
Above all else though, just be yourself. If they love you, they love you, if they don't, they don't. You want to be in a sorority that embraces who you are completely, including what year you are.
I wish you the best of luck!