I am the voice for the band, which means I have patter, speech, commentary, jokes, etc.
But I doubt that resume is key to this particular discussion other than the fact that I speak to groups as small as six and as large as 6,000. In all respects I always speak to one person in the audience, thus have no fear. Then again, I've been doing it for nearly 42 years.
edit: Meant to add that I do IT and computer based speech as well... just relating how I got my confidence.