With audiences, pick 2-3 people that look focused and use them as anchor points

Speak facing the audience, especially if you don't have a mic

If you are using a projector, pay attention to the colour scheme/font size, usually, light themes are more readable.

Give them a promise, if you follow along with this presentation you will know how to do X. Eg:

Have you ever had issues installing the environment in order to develop for a board? Did you want to try your code but you just burnt your sensor or broke your board? By the end of this presentation, we will know how to bootstrap those issues