Consider what your audience is trying to achieve or overcome
Whether you write an article, design a talk, or create a podcast, you do it for your audience.
Your content should always be designed to help your audience achieve something or overcome a challenge they experience. Considering the things your audience is concerned with will affect any decision in writing the content, from defining the subject to deciding how to phrase an idea and which examples to use.
Slides come last
When you design a presentation, the slides should always be the last thing you work on (if you need slides at all).
Treat your presentation as if it is an article or a speech. Define your goal: what impact you wish to create. Collect raw material. Process it and arrange it. Only when you have a complete design of what you want to say you can decide how will the slides serve it best.
Never start with the slides, and avoid designing your presentation by dumping ideas on slides.
Don’t try to cover the entire ground
When you write about something you are well familiar with, it is easy to get carried away and capture as much of your knowledge as possible. This is rarely possible.
Whether your write an article or a book, a short talk, or a complete workshop, chances are you will not be able to cover the entire ground. Before writing a single word, you have to make a conscious decision: what scope you aim to cover.
Sometimes you will have to refine this definition as you work on your content. But without making this tough call to begin with, you will not be focused.
When you aim for everything, you will achieve practically nothing.