My best advice for you is to just be free don't be to stiff but don't be to loose go with the flow of the music and let him lead you. Also don't think so much about the fact that he is a boy imagine him as just a great friend. Hope this helps
Me being a boy, I may be able to help you out with suggestions that we may notice. First of all, don't even think about being nervous. Just have fun, laugh, talk and overall just have a great time. Us guys want to see you having a great time. Just flow with the music. My main advise is just be you! The boy is dancing with you for a reason! :) So just have a good time and don't even think about it, just have fun!
