Delivery

Voice, pace and pauses.

The basics

Speak more slowly than feels natural, pause after important points, and vary pitch. Filler words mostly disappear when you become comfortable with silence.

A pause feels much longer to you than to the audience.
Look at individual people for a few seconds each, not at the back wall.

Nerves

Physical arousal is normal and largely invisible. Rehearsing aloud several times is the intervention with the best evidence; deep breaths before starting help the voice.