Only time for a short answer right now, but I'm happy to help somebody who has the passion and is serious about approaching the work as a career.
I'd first like to draw the distinction between two issues, both are important to success, but are sometimes only distantly related:
1) Developing skills as a performer, ad-libber, and motivator of on-stage action.
Appearance and charissma are the wild card prerequisites that you must bring to the table. Above that you build the skills by hundreds or thousands of hours of trial and error, performing in gigs such as stand-up, disc jockey, audience warm-up. corporate speaker, talk show host, stand-in for TV personalities, traffic school instructor, or other activities that put you in front of an audience, interacting with other humans, motivating the conversation or action.
2) Exploiting success, fame or notoriety from another pursuit.
The "suits" seem unwilling these days to gamble on an unknown. While sports figures, actors, and trial attorneys have gotten their shots, I believe that popularity in more directly related entertainment or broadcasting pursuits will usually tend to yield greatest success.
There's no school or predictable path. You create your own opportunities, luck, synchronicity and serendipity. Believe in yourself, be focused and tireless, network, observe and seek mentors.
Good luck. I'd welcome the chance to say, "And here's our host, DoorNumberFour"!
Randy
tvrandywest.com