Other than having confidence and talent, what must one possess in order to be a great extemporaneous speaker

Question

Other than having confidence and talent, what must one possess in order to be a great extemporaneous speaker

Answer 1

must have wide general knowledge and good in language so you will win!!

Answer 2

The ability to organize thoughts quickly.

Vast knowledge on a wide range of subjects.

A quick wit / good sense of humor

The ability to improvise

Answer 3

Practice.  

Answer 4

Inspiration and instill in the audience the desire to do or create or be whatever the speaker is trying to convey. For eg. Hitler was a great speaker. (although not much else)