To some extent the point I want to make I'd similar to the one made by reuven elsewhere in this thread, but I think it is still different (and maybe shorter? we'll see ;P) enough to still post. (OK, after writing, this failed at my goal of being shorter ;P.)

So, I also do a lot of conference speaking, albeit nowhere near as much as reuven. I remember in high school, public speaking was terrifying. By the end of college, I was giving one of the graduation speeches.

The difference was not me becoming better at making arguments or telling stories or being prepared or building slides or really anything about what I said on stage: the difference is that I felt at home there.

In essence, I had the fear of public speaking that many, if not most, people have. This fear is mostly about people watching you and judging you. You are concerned about where they are looking and what you are doing: it paralyzes you.

It had very little, however, to do with what you are doing in front of everyone: you could be on stage being told "eat breakfast as you would on a normal day" or simply a lunch meeting where you are standing due to lack of chairs while everyone else is sitting.

I don't feel, therefore, like helping people present is the solution. I will say that it might try to ease the person's anxiety enough to consider doing it once, but that isn't why they are afraid: I am not afraid of bungee jumping because I think I'm going to die due to the cord breaking, I'm afraid of bungee jumping because even looking at a photograph taken from a high-up location makes me curl into a ball.

These fears can be so bad that they aren't obviously fixable (phobia-level fears can be like that). In my case, I likely have acrophobia (heights), but as something of a "class clown" when I was much much younger, I can't ever claim to have had glossophobia (public speaking). My fear was mild, and I tackled it.

I want to be very clear, though, that there is a difference between "preparation" and "lack of fear": if you told me to go stand on stage right now in front of a thousand people, I'd be happy to do that. I would be willing to try to entertain them. I might fail, but I don't mind anymore.

I might thereby recommend more doing something structured that tales away all of the "things you can do wrong" variables entirely before bothering with trying to prepare those away: take an acting class. You are told exactly what to say, you have a director guiding your movements, and on the show day a perfect performance can be identical to the previous day. You don't have to worry if what you are saying sounds stupid: you have no choice in what to say.

(That said, I wouldn't "recommend" it strongly, as I think a lot of these shortcuts in hindsight by people who have defeated something others find hard are missing the point of what made it work for them: that you probably just need to be doing it, constantly, for long enough, to make it easy. This is similar to the "monad tutorial fallacy" in my mind.)

Then, when your fear of being in front of people is gone, maybe the preparation isn't even that big of a deal: if you are comfortable, the audience will be comfortable, and you can "get away with" a lot more on stage.

I mean, preparation is great, but "public speaking is tough" is not because "writing slides is tough" or "answering questions is tough", it's simply tough because "public anything is tough"... you answer questions every day in the hallway: you don't need more preparation to do that on stage, you just need less fear (which again: isn't easy).