That only charismatic, confident people can pull it off. I have done some public speaking, though not a lot. The first 5 minutes are the hardest. Here is what I do when I know I have to speak:
* I prepare very thoroughly.
* I write down key points, not a script. I keep my notes short and sweet. Too much information will overwhelm you.
* I try to come up with good illustrations for points I want to make.
* If appropriate, I use some humor
* I look at my audience, which is hard to do yet for me, but I force myself. If a person I look at has no expression on their face, I cannot assume he is not interested in what I'm saying, but I do look at other faces then and let them know i am speaking to themm, not just to the air.
* I don't panic if I miss a point or stumble over words. Everyone does that. Nobody cares. You can either keep going, or make the correction calmly, possibly humorously, and/or confidently.
*Practice, practice, practice. Not neccessarily out loud, but that wouldn't hurt a time or two just to get the timing write (can I do this in the alloted 29 minute time period?) I mentally prepare. Not script like, but what in general I'm going to say, the key points that are most essential.
* The morning I know I am going to speak, I don't spend the hours leading up to my talk going over and over and over it. It only builds more stress. Take a few minutes and look over your notes then relax. If your uptight while talking, it will show.
* I am myself. If I try to be like someone else when I speak, I fall flat. People can spot of phony. As long as I know what I want to say, I am okay to be myself. That's where you get your confidence.
For half my life I was terrified to speak in front of people. On oral book report day I always faked being sick so I didn't have to do it. I was a wall flower until well into my adulthood. At one point in my life, I started paying attention to friends and family members who were very sociable and learned some things about how to converse with people. I got involved in things where I had to hear speakers, not for that reason, but it just happened. I pay attention to the better speakers and determine what makes that person such a good speaker. I just plain pay attention and learn from others.