It's actually a pretty hard thing to do, becoming a comedian. People like originality, or at least I do. Like the new Comedy Central show "Mind of Mencia."
Before Carlos Mencia got on Comedy Central, he played once on Comedy Central Presents. That was the funniest thing I had seen in a very long time but than his show came out and it wasn't that great. He was basiclly trying to imitate what Dave Chappelle was doing in his show.
I think you need a subject which you can make tons of fun of. Something that's always changing. Take the political themed comedy show "The Daily Show with John Stewart"
Politics are always something people are concerned about and something that's probably always going to be around. The idea is based around making fun of the government because not all that many people fully agree with the decisions politicions make.
What I'm getting at is that you need a popular, interesting topic or theme to base your comedy upon. Than you've got to deal with stage fright and all that crap but that's another topic.
I wish you luck.