Don't, the first Civ III demogame I participated in was on monarch level I believe, when I was still playing Noble.
By participating you will help to improve your own skills as you watch other people discuss strategy. You give in your opinion, and you might be surprised that people will actually listen to you.
Even those who play lower difficulties have something to contribute. Your weaknesses might be micromanaging production over an entire empire. However, you still could contribute to general military strategy, or research. Or improve your own micromanaging skills via a governorship, where you only have a few cities to keep track of. And even then you have the resources of all the other citizens here.