[silvestrov]

I think a major part of being bad presenters is that they don't train but think that they can do well with just a quick go-over of the materials.

Becoming good takes a lot of hard work, lot of redoing of stuff. Just like becoming good at soccer is more than playing games. Many successful YouTubers have learned it's hard work to make good videos.

Like Penn&Teller said: The only secret of magic is that I’m willing to work harder on it than you think it’s worth.

[parpfish]

if i'm giving a presentation, i always practice it several times and i always find flaws to fix up(there's no segue from this slide to this one, i need to reorder these so i can introduce X before talking about Y, etc).

but you have to practice the right way.

the terrible, long-winded, confusing presentations you've seen were most likely done by somebody that sees a presentations as merely "talking in front of a group" so their practice would be focused on memorizing lines/facts that want to say. they may sound polished, but it's not necessarily going to be good.

in order for your practice to actually help, you need to go through your presentation while maintaining a strong sense of empathy for the audience. you need to fight a constant battle against the 'curse of knowledge' and force yourself to honestly evaluate what you're doing from the perspective as a first-time listener.