unbelievably this isn't a wind-up:

"1. Use mirroring (do it, and they'll do it back)

When you arrive onstage at a gig, it's vital to realize that the crowd wants to like you. Providing them with physical cues to express their support is the ideal way to break the ice – all it takes is a little physical mirroring.

The first, and most striking, example of mirroring that goes on between artist and audience begins before the start of the set. We've all been in the audience and seen performers clapping towards us as they come onstage. And we've applauded right back to the people we've paid to see. There is no moment when the Show Business Fairy lands on your pillow and whispers that you have attained the right to applaud. Walk onto the stage, approach its edge, extend your energy into the room, and clap towards the onlooking faces. Watch the mirrored response this will illicit even in a tiny venue. During the set, and at the end of your songs, applaud the audience and watch them as they return the gesture, creating that unmistakable sound of a gig going great"

http://blog.sonicbids.com/6-stage-hacks-to-engage-a-crowd