Amazon will have you work on micro-projects that require some sort of human interaction. Tasks can include translating a paragraph into English (or another language), rating the search results for certain keywords, or reworking an article. The tasks are simple, and you will be paid a small amount to complete each. But if you do enough tasks quickly, you can make a respectable amount of money.
The topic you choose must have enough depth that you can create a lot of content for it. This is important for building an authoritative site, for search engine optimization, and most importantly, for the end user. If you don't have enough content about a topic, you're not going to be taken very seriously as an authority on the topic and it's unlikely you can convince someone to make a purchase from you. 
In the last couple of years, several high-profile brands and influencers (Warner Brothers and the Kardashians, to name a few) have come under scrutiny for failing to disclose paid advertisements. Along with this enhanced focus from the FTC comes the new General Protection Data Regulation (GDPR) regulations, ensuring affiliate marketers will be more focused on compliance and transparency than ever before.
Next, you’ll want to pick a WordPress theme from somewhere like ThemeForest, Elegant Themes or OptimizePress. This is the barebones design of your site, which you can then customize with your own branding, copy, and images. That being said, you don’t want to cheap out. It costs less than $100 to buy a theme that will make your website look professional (and you can upgrade to a completely custom design once you get the business going).