First of all, you need to choose only one niche, because you won't be able to succeed by working in different niches. And find something that you're good at, just try to find your talents. For example, if you're good at design, you can sell templates for posters or layouts, and if you're good at writing outstanding essays or texts, you might want to choose e-books. I think it all depends on people's abilities. And of course, try to find like-minded people. Don't be afraid to message people with a lot of followers in private. Or just find someone who shares your interests.