"You look nice tonight."
Women may be used to hearing physical compliments from men, but it's not always so the other way around. A simple, "That sweater looks really nice on you," bolsters his confidence and puts him at ease. Be wary of "you're cute" though; it makes a guy wonder if you think he's a puppy.
That You Think He's Funny
Don't ask him to tell you a joke, but if he says something funny, feel free to laugh your head off.