My experience in side hustles is limited, but I'll describe it: I did various freelancing gigs on Upwork and Fiverr, mostly comedy writing (which turned into my main job), and I self-published erotica on Amazon for a while (I might get back to it).

I'll approach this from the perspective of someone interested in side hustles and from the perspective of someone running an online service business for not very long (I'm still mostly working on it by myself).