You’ve probably heard that title before. This is not a scam or personal promotion, this is just my opinion and experience.
Who doesn’t want a little extra cash, the problem is how to get it. There are many ways to do this. On the internet usually the best way is to own a website and put ads on it. A very popular ad network is
To drive visitors to your website you can spend some money to advertise, or you could do a link exchange. Another way is to include it in your signature on forums, just don’t spam.