If you cannot find a specific product in an affiliate marketplace, then check out the brand’s website. Many companies have established affiliate programs that accept applications. Some companies choose this method to create a more exclusive affiliate program. Typically, these programs have stricter audience requirements than affiliate marketplaces, but it is still worth a try. When in doubt, apply for the program.
Etsy: While Etsy's popularity has declined recently, it's still a great resource for selling handmade items online. No need for complex ecommerce sites or merchant accounts or any sort of automation. The company takes a commission of every sale and charges a small listing fee per item. But many still use Etsy as their primary source of income. The best part is that you can also sell digital products on here such as poster designs.
MozBar – MozBar is a Google Chrome extension that lets you Google any keyword and see how competitive the search results are. The higher the DA (domain authority) and PA (page authority) the more competitive the keyword is. However you still want to click on the top results and browse the content to make sure you can creating an article/video that is better than whoever’s in the top results. That is really what “researching the competition” is all about.