I started with the usual blockout for the shapes and then adding details bit by bit, experimenting with stuff as I move along with the scene, but since the scene was pretty simple I didn't have to experiment much.

I loved the eyes without the glare but I wanted to keep that artificial toy porcelain look so I added the white plastic-y glare.

The scene looked boring since it's just the simple character without much going on so I added the opening for the chest and the heart inside.

Added a simple texture for the circuit inside and a glass heart with a sphere and light inside.

At first I had no subsurface scattering material to reduce render times , then I added a little bit too much that the ears started to look transparent, so I reduced it a little bit till I reached the amount I wanted for the skin material.

usually I try do the lighting of a scene with 2 or 3 lights but I add more if the scene requires so or if it would add something to the story.

Here I added the usual 3 point light system: main, fill and rim lights, and then I added one light in the back for aesthetics and one in the chest for the heart