Studies NSFW (Patreon)

One of the major abilities to learn as an artist is correctly overlapping shapes in your drawings. It was always a hard subject for me to master, and it took me a lot of practicing to actually get into a place I am today (which is still far from being mastered, yet way better than the miserable beginnings). I experianced a big growth while doing studies of hands, feet, mouth and nsfw. I would dare to say these are the best teachers if it comes to learning how to overlap shapes correctly. Complexity of the shape and/or softness of the tissue, like for example lips or labia, are the best qualities of those body parts. Sure, they may be awfully frustrating to draw, but in the end mastering the skill of drawing them is highly rewarding. Indentation of the soft body parts and interaction of objects with those makes the drawing seem more alive, more organic. 

When i work with a drawing that is focused on overlapping i try to imagine it in 3D and often ask myself questions like: 

"What is closer to the eye?" - a shape that is closer usually will be more rouded and soft while covering some of the shapes behind it.
"Where is the force directed?" - sometimes a good way to indicate a force's direction is to make a very visible distinction between soft rounded shapes and a more sharp, sometimes pointy angles of force and the place of "the impact"/interaction.

These are some of my private notes as i gained a bit of experiance through out years of self studying, but I'm by no means an expert. Experiment. Practice without feeling ashamed of failing. It's a part of the process.