The essentials of public speaking are 5: The audience, Message, Research, Rehearsal and Improvisation.
These are just tips to help you after listening to the audio:
When and where is the event? So you'll know general context.
What's the main goal of the event or the topic they want you to cover?
What's the audience profile? Occupation, age, mother language, level of understanding of your topic.
How many people are going to be there? Is it live or online?
Is it a talk or a workshop what do they need?
And, How are they promoting the event?
What do you want to achieve?
Then, plan the story:
Point A, How will your story start?
Point B, How will it end?
Who are the main characters and what's your role in the story. (You can be only the narrator or the protagonist)
At last, what happened? How 'point A' got to 'point B' for the characters?
Which statistics or facts are related to my message?
Is there any recent news about my topic?
What have the thought leaders said about this?
How does that support my story? It contrasts it or highlights it?
Create mental bonds.
Practice with your slides next to you while reading your texts. So you can bond the message with the image on each slide.
What's the core purpose of the talk?
What's the message of this slide?
What did I already cover?