What shows authority and power?

Via The Silent Language of Leaders: How Body Language Can Help–or Hurt–How You Lead:

As a leader, you show authority and power by your erect posture, command of physical space, purposeful stride (like that of Apple’s CEO Steve Jobs as he moves across the stage during a presentation), and firm handshake, and through an array of hand signals including “steepling” and palm-down gestures that send nonverbal signals of authority.

so you're saying I should do this:

Source: http://www.sierraclub.org/solar/sierra/2014-6-november-december/green-life/how-strike-pose-save-your-life

You got it. Big and scary is a show of power!

And what communicates warmth?

Via The Silent Language of Leaders: How Body Language Can Help–or Hurt–How You Lead:

As a leader, you communicate warmth nonverbally with open body postures, palm-up hand gestures, a full-frontal body orientation, positive eye contact, synchronized movements, head nods, head tilts, and smiles.