If you sell life insurance and annuities for a living, the ability to speak well at seminars and other events can help you persuade more people to protect themselves, and their loved ones, against death, disability and longevity risk.
Be very careful about the advice you take on this subject. I have been speaking to groups for 44 years. I have read endless articles on the subject of public speaking and most have been debunked.
Voice training, posture, power-point, no power-point, dress for success, dress to audience comfort and on and on. There is only one significant piece of advice that will take you further than all of the details on micro issues: Repetition.
To get better at speaking, you must speak to live audiences. I have been told that I am an effective speaker. My financial practice proves that as fact.
I present seminars and earn commissions because of audience response. If people are persuaded by what you have to say and how you say it, you are an excellent speaker. If not, keep practicing.
When I was running a printing press at 19 years old a salesman came into our plant to sell supplies. As I got to know him, I decided what he was doing was better than what I was doing. I took sales courses and learned that somewhere in the process of selling I needed better skill sets in persuasion.
Learning to sell printed products was one matter but being an effective speaker was quite another matter. I joined Toastmasters and learned how poor a speaker I really was. After making no real progress for a year an older and wiser fellow in the group told be that I was trying too hard and that emotion sells.