Loop/cycle over the same content multiple times. At any point, only 80% of your audience are actually engaged.
Build fences. When you outline something that you're explaining, also explain the things that aren't your thing. For example, if you are showing what is book, explain that a book is also not a comic, and it's not a laptop. This helps to remove the audience's preconceptions. Or "my algorithm might seem similar to Joes except that his is exponential and mine is linear".
Use verbal punctuation. Because some people are zoning out, you need to provide some landmark spaces for them to get back in. Usually you can outline a structure up front, then each time you "move" to a new section they can re-engage.
Ask a question and then pause. Helps to tune back in. Don't make the question to easy otherwise people will be embarrassed to answer. Don't make it too hard otherwise it will be to difficult to respond.
Avoid run-on sentences or not pausing enough between important sentences. If you have tendency to hurry up, it's less convincing and memorable. If you stop after a sentence, it sounds like you said something important and emphasizes it.
Avoid "Uptalk". This is the habit of ending all sentences with rising sound. Everything sounds like a question.
Some male speakers have tendency to start sentences in discussion with high pitch fast speech that slows down towards end. Even some very high profile journalists and podcast hosts have it to some extent. Ezra Klein for example.