This is a collection of notes on making a presentation.
Of course, this is not all my own advice but things I have learned and picked up from friends and colleagues. Many thanks.
Slide numbers not only help you see how far through you are (for timing) but also your audience. They can also be useful for when people have questions... which they will.
Having a rough table of contents (for longer talks) helps the audience see where you will go. Periodically going back to this helps them see where they are. Also, some people might tune out for sections so give them an easy chance to come back.
You'll gradually lose people (through tiredness and confusion/disinterest) so state the problem early, state it frequently and state it clearly. If the problem isn't simple (or you have a nice way to describe it) then the solution likely isn't simple either.
On that note...
Have a problem you are going to solve in the presentation. Big or small it gives you and your audience something to focus on and a shared point of reference.
After stating your problem, maybe (hopefully) there is a quick one-liner version of the solution you'll be talking about. Present it early, frequently and clearly, like the problem. If everyone tunes out after this that's fine, hopefully they got the message.
No, I don't just mean having the wrong screen up, as bad as that may be for the whole talk. Speaker notes belong in the notes, for you. Replace them with graphics or questions related to what you're saying and keep any text full enough that they could understand it without you talking.
Talks are rarely lectures, at least outside of University. Focus on the interesting bits and make them fun with relatable examples. Trim out unnecessary information guiding the audience on a clear path. No tutorials.