A very common question from cosplay models is "What should I do with my hands?"
Well, whenever we look at a scene with a person in it, our attention is naturally drawn to their face and their hands, because these are usually the best clues to what is happening. So for the viewer, the face and hands occupy much more "mental space" in the photo than their actual physical size. And hands are big -- they are bigger than your ears, bigger than your nose -- we don't usually think of them as large, but they are. If you combine all that with a pose where the hands are closer to the camera than anything else, all of a sudden the hands seem huge!
So the rule is simple: your hands must either tell the story, or get out of the way and be less noticeable.
Examples of your hands telling the story would be things like: throwing a punch, reaching out for the hand of a friend, casting a spell, lifting a drink to make a toast, making a gesture of prayer, picking someone's pocket, etc.
But if your hands aren't going to tell the story, then you want to make them less noticeable, by doing things like: moving them farther from the camera, turning them edgewise to the camera, putting them behind something, putting them under something, etc.
It's really that simple. I was originally going to explain this in a more complicated way, but I realized that it all boils down to this.
Hands must tell the story, or get out of the way.
That is the main thing you need to know about hands.