This curiosity I found in many new comers. One thing you remember that the earnings are only a part time just like a pocket money. If you want to earn huge money from these sites, the best way is to buildup the content which catches the page impressions by the net users so that you can earn good amount through adsense and kontera affiliate programmes.
For earnings you have to be on net more and more time and goes on participating in forums, resources, reviews ( $ marked products will catch cash rewards too), adding products, business etc.,
Have a nice time.
RK - Some thing special