I do this because I want to build a solid reputation and a loyal readership of people who trust me. I’d rather make less money and still have a reader than make lots of money and never see the reader again. For me, this comes not only from my ethics but my belief that in the long term building a good profile and reputation leads to other opportunities for profit. 

Find work. When you first start out, you may have to accept work writing about a topic you don’t find all that interesting. You must keep an open mind and be willing to accept work that may not be in your desired field. However, as you continue to write, you not only learn about more topics, but you also build your reputation. With time, you can be choosier about assignments you want to accept.[19]
What’s the catch? None, really. Cash back apps act as affiliates for many online merchants, which means that whenever you make a purchase through one of the apps, they get a small commission — but then, they give you a portion of that commission as “cash back”. For example, if I buy a pair of Nike shoes through the Ebates app (or website) and spend $75, Ebates may get a $10 commission but then they’ll pass $7 back to me. It’s basically a way to get sale prices on stuff that isn’t on sale!
Mechanical Turk is Amazon's take on micro-jobs. These are small miniscule-jobs that you can do for other people, which they call HITs, or Human Intelligence Tasks. These are super simple tasks that anyone can do. Some examples are listing off some URLs with certain kinds of images for one cent, or recording a few phrases with a microphone for 6 cents.
Webinars are quite possibly one of the most potent ways you can make an exorbitant amount of money online. You'll need an audience to train and you'll need to know what you're talking about. Of course, this usually requires having a website and some semblance of an online presence. However, people can still do webinars without all of that. For example, you might have a sizable social media following and you train them every week on something to do with social media. But you will need a product to embed and sell at some point. Don't worry about it in the beginning. In my experience, the best webinar platform out there is GoToWebinar. 
Regardless if you need to earn some fast cash or we're just talking about making money in the grand scheme of things, there's an important psychology that needs to be mentioned before getting into the strategies. If you study Freud's model of the mind, you'll discover the Psychic Apparatus. It's the three-part construct in your mind that controls all of your behavior.