After years of experience, I deduced the single most important factor that makes a person overcome the fear of public speaking and determines how good a presentation one can deliver. If 80/20 rule was applied here, this factor solves the core 80% of the problem.
One can find many techniques and training courses on how to master public speaking and give a great presentation. I think that all such methods affect the relatively insignificant 20% only (while polishing the presentation skills though).
So what is that single factor that is the key to be a fearless speaker? Well, you already know it and might laugh about how simple something can be.
Fear of presenting to a group in a room is directly proportional to the difference between one’s knowledge and that of others in the room.
It cannot be more straightforward than that. If you have worked so hard on something that you know more about it than anyone else in the room, and then you have prepared a reasonably good presentation, you don’t have anything to worry about; the fear will seek someone else.
It should be kept in mind that it does work to some extent in the case where you focus all your energy to prepare a presentation on one particular topic. Mostly, however, it holds for the expertise that you gain from years of excelling in your specific profession or hobby.