I would say keeping "just ahead" of the beat so to speak that gives beat driven songs that drive forward. Also, having character and emotion to your voice will add a deapth of intrigue to your music that turns a performance from a medley of voices, into an artists' performance, if you will. Your music can't truely effect your whole audiance, if it doesn't effect your performers. If they can relate and express something of themselves through the music selected, then this will become a whole lot easier. That's just my two cents. If all else fails, i suppose you could just change the batteries.