If you are serious about earning money online & you are a hard working guy who wants to make big income then affiliate marketing is for you. There is more scope for affiliate marketing than before because of the high growth of online shopping.There are hundreds of online merchants like Flipkart, Amazon, eBay, Clickbank, CJetc. where you can signup & promote their products.In affiliate marketing, you are simply helping customers to buy the right product by creating a simple website & in return you can earn 4% to 20% commission.
Although this one is the most favourite in my list but I put this in #4 because its not as easy as other 3 above & it takes time to make money from Google AdSense. You need a website (which anyone can create now a days) & some tricks to bring the traffic on your website so that you can earn money from AdSense & other ad network.
Freelancing is another popular way to make money after AdSense & affiliate marketing. As a freelancer, you can work with small or big companies on a temporary basis & provide them your services. Freelancers can make $500 to $2000+ per month depending on the type of skills you will use as a freelancer. There are dozens of popular websites like Elance, Freelancer.in, WorkNHire, Upwork, People per Hour etc. that can give you the ready platform with ready clients.
Content writing is a form of online writing which is closely linked to web marketing campaigns. This means creating the writing which appears on websites that are designed to sell or promote a specific product. Content writers work according to the brief provided by a client.