Alot of research. It takes so much trial and error that people just aren't going to share their methods.
But seems the main hustle people are doing is refunding.
When i think of ways to make money i always think what value can i add to something that already exists? For example lets say you're skilled at drawing cartoons. Buy some plain tops and print on your designs or design signage for shops. Also remember you make money by finding solutions to other peoples problems.