Google Ad Sense can work if you have a high traffic site and high priced key words, choosing the right keywords are very important when starting a site, take this site for example it will not do well with Google Ad Sense. I know your asking your self, why start it? Well this is a good starter site, one where I don't expect to make money, I expect to make friends. a good healthy goal i set for myself right. All great social networking sites start by trying to provide a service that will help there users communicate. look how well some of these site are doing now.
keep it simple and start something that's what I'm thinking. your first site may fail, thats OK, just keep trying. click for here for a good article on starting a niche blog.