Title says the most of it.

As a little background: Given the circumstances, I'm starting to reap the benefits from the most of areas in my life that I invested in - Gym, game, posture, hobbies, confidence, etc.

However, firstly, there's this thinking on your feet/quickly critically judging the issue at hand part that I am having troubles with. Secondly, even if I do come up with a solution, reply, or a statement of a particular position in time, I'm usually having hard time expressing my thoughts in understandable, but eloquent manner.

Here and there, I come across a person who just seems to get it - digests the newly introduced information in a jiff, dissects all the related details, and communicates his/her opinion in a way that is easy to comprehend, but also extremely rich in language.

I am willing to put in a lot of work to get there. How do I achieve that? (Any books to read? Videos on Youtube? exercises? Anything) I would also like you to share personal experiences/journey, if you have one, of transforming from an illiterate scrub to a charming spokesperson.