Producers make anywhere from $50 to $500,000 a track. He is also in charge of the creative mix. If you're a new and up and coming producer, most will suggest that you start doing work free just to get your name out. You can also bring on some artist yourself, blow them up, then everyone will be asking who produced those tracks. There is definitely a lot of money to be made if you have enough perseverance and talent.
A producer should be enthusiastic about music and the artist. One who is an expert in the genre that they work in. You should be able to give constructive criticism, and develop an honest and successful relationship with the artist. Who you know is everything in the industry.