Understanding a shy guy (social anxiety)?

I like a shy guy and I'm probably just as shy so I really can't muster up the courage to actually go and talk to him... Without actually talking what are some common body language signs used by shy guys? He sits a few seats behind me in a different row. He walks like he's scared of something half the time. His slouches and his legs always seem to be pointed towards my row. Some days it's gotten to the point where I've almost tripped over them.