Think of body language like not playing with a pen, sitting upright, not slouching and speaking clearly.
Think about your responses.
Try not to oversell who you are.
Do not be fearful to declare you don't know an answer.
Put on a clean suit. Wear it sharp and clean.
Do not use unprofessional terminology.
Suggestions for those looking for employment:
"While reading your CV, ask (trusted) colleagues to go over it before emailing to a new company. If you spend time on such documents for a long while, your brain can amend the words you are looking at in error."
Key things for this position:
Is able to operate during extreme pressure
A capable teammate, adept enough to initiate friendships
An aspiring and enthusiastic ethic
A colleague who doesn't mind to 'chip in' whatever the problem