If you had a demo CD what would be the best way to market it?

Who would you want to give it to? This would all be in anticipation of a recording contract. What would I want to not do with it? I just want to know if anyone has had any experience with this step of recording so they may be able to give some pointers. Like would you send a demo to a radiostaion or should you wait? I have a lot of questions any answers would be helpful. Thanks