Presence

Body and space.

Physical basics

Stand where people can see you, plant your feet rather than pacing, and keep your hands free to gesture naturally. Gestures that match your words help comprehension.

Avoid hiding behind a lectern or a laptop if you can.
Dress slightly more formally than the audience; it removes a distraction.

Authenticity

Copying a confident speaker's mannerisms reads as performance. Speaking as yourself, prepared, is more persuasive than any technique.