How should I start a conversation with a guy in my class?

This guy in my social studies class is smart,funny,and nice but i’ve noticed he doesn’t really talk to anyone. I mean hes talked to me about four times this year which is pretty good considering that I never actually made an effort to talk to him. I know it sounds bad but he was always around other people or something like that.
Anyway he was sitting by himself Friday at lunch and I wanted to go over and talk to him but I didn’t know what to say. And believe it or not i’m not a shy person. It was just weird I guess. He doesn’t talk much and if he does it’s usually to me. With other people he likes to be seen more then heard, in a sense. How can I start a conversation with him? Thanks