Many good answer has already been given.
I think if your goal is only earn money than its not a website where you invest and earn money as a return. Because main goal of this forum is talked about bitcoin as obvious from its name Bitcointalk . but if you have little bit knowledge of bitcoin than you have a good chance of earning by joining signature campaign and bounty offered by many companies. Try to talk about bitcoin. I hope you will get your goal here . keep it ip.