Along with your art style, it can be helpful to identify an "animation style" as well. Results in the Spine animation can vary depending on your animation style and current production objectives.
I cut up my layers in a very advanced way. This includes a full facial rig and hand rig. The face rig consists of a "head" with the eye and mouth cut out. What's behind it are: "Sclera", "Iris", "Inner Mouth", "Tongue", "Teeth". In front: The Eyelash and Eyebrows. The "hand rig" is something I don't recommend for most people, but I can do a full range of hand poses with the finger layers.
Separating the body parts, in general, is the standard way for Spine rigs. The complex part after this is setting the weights (Pro).