I think besides the obvious, being able to play the guitar, you have to show that you are genuinely involved in what you are doing (making music) without appearing self conscious. If the audience knows it's real, they'll respond. This could mean jumping around like madman, setting your gear on fire, making strange faces, goosewalking, or simply standing still with your eyes closed or sitting in a dark corner of the stage. You've got to be comfortable with whatever you do or else you won't play your best which is job#1. Some players entertain you with their unconscious movements. I knew a guy who used to swing his leg when he was really into it. It was totally unconscious, something he had to do to play well, but people found it entertaining. Like I said, genuine involvement is the key.