Your personal appearance on stage speaks directly to the audience even before you said the first word. Stay grounded and keep a stable posture. This is create a confident appearance and help you out in the case where nerves take over.
First thing is to keep both feet on the ground. This might sound obvious, but it is not uncommon to have a bad posture or ‘hang’ in the hip. A typical posture is leaning on one foot, giving almost no ballast on the other foot. This gives an uneven weight and does not support appearance, voice or confidence.
Secondly, try to keep shoulders behind the ears. Shoulders that fall forward will not only give you a bad posture, they will also affect your voice as it applies unnecessary pressure.
A trick is to imagine a rope tied to the tip of the head. Imagine someone is pulling that rope upwards and your body naturally follows. This posture will be natural for you and not create unnecessary ‘noise’ to look at.
Free movement is of course up to the speaker. Using the stage and room during a presentation is usually effective and keeps the audience’s attention. The point of having a good base position is to know where to go, when the movement slows down or you need a small break to gather your thoughts and get back into the structure of you talk.
The body language of a speaker is like a house: the creativity has almost no limits, but the foundation needs to be solid, stable and robust.science-communicator.com