Using Fiverr is a great way to pick up work. Once you have signed up you can advertise your services. Fiver allows you to create your own gigs, whether you are offering web design, digital marketing, writing, or something else. You can choose how much you want to charge (it can be more than a fiver) and people will then contact you if they are interested in working with you. Fiverr will not only help you get experience if you are just starting off as a freelancer, it will also help you earn some extra cash.
The products and services you will be promoting to your audience must be relevant and good quality. Make sure you believe in them and know everything about them, because this will be crucial to you delivering the sales pitch to your audience. You need to build trust with your audience so make sure the products and services you choose to promote are trustworthy enough.
From what I’ve observed, most of the “programs” you’ve listed are networks, and most of them support dozens, hundreds, even thousands of merchants – in a huge variety of niches. Amazon is not technically a network, unless you factor in the presence of about a dozen entities like Zappos, Woot, Endless and the like. With very few exceptions, networks are diversified. Performance-Based.com focuses on eco and green merchants. Some support a particular locale – European merchants, for example.
If you have a good idea for an app, and the skills to create it, then producing your own premium app can be profitable. However, with so many free apps available, it may be hard to convince people to pay. If you want to go down the premium app route, consider having a basic free version to encourage people to download the app in the first place. You can then provide the option of upgrading to a premium plan once users realize how useful the app is.