I don’t know of any specific tutorial, but personally I would just grab a real toy and examine how it’s joints work (there only tends to be a few different kinds). Usually it’s the same concept: a gap in the torso wide enough for a piece to fit into and move around, but not wide enough to let it escape.
Then you could either try to find out the specific accuracy of the printer you’re using so that you’ll know how much of a space to leave between parts in order to ensure that everything gets separated correctly, or you can print the thing in parts and assemble the pieces afterwards.