There is not a lot written about humor in photography. There are some very humorous photographers - Elliot Erwitt immediately comes to mind.
Unposed typically, rely on juxtaposition, moments, angles, composition. Not something constructed in the studio. That doesn't interest me. Humor found in daily life and interactions between people, animals etc.
I think a lot of humorous photography starts with a photographer who has a good sense of humor. If you don't have a sense of humor or don't have any idea how to make someone laugh or enjoy other people's laughter, you probably aren't going to take a great interest in seeking the visual humor in situations that create/provide humorous photos. I don't mean making fun of people either. Or maybe you do a little, but when engaged with a subject, there should be some connection and follow-up on any photo, so you could determine if the situation was seen as funny by all etc.