How to get rid of side-stitches when running!?!?

I have a cross country race tomorrow, and I am really nervous because I want to do well, but I usually don't because I ALWAYS get side-stitches. I have heard that you are supposed to exhale as your left foot goes on the ground. I get stitches on my left side, so does that mean that I should exhale while on my right side?? Thnx