Spanish and famous psychiatrist Vallejo-Nágera wrote something about talking in public.
The first piece of advice was to be naturalistic, to be you yourself, and show as such. Even you can say you are not used to public presentations and you’re going to do whatever possible.
The second piece of advice was to speak for a short time: your audience ought to become wishing to listen to more but the thing is over. / Photo from: bemidjstate edu