Think of body language like not playing with a pen, sitting upright, not slouching and speaking clearly.
Do not go off topic. Keep your thoughts on the things you are good at.
Make a Google Alert on the firm to know latest developments.
Analyse typical questions and write down your replies.
Advice 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."
It may be nice to have:
Organised and strong administrative capabilities
A confident communicator with the capacity to deal with all
Ability to interact well with people at all levels within the organisation with excellent communication skills
Be able to demonstrate energy and passion as a leader