I find it easiest to model the head in modelling clay. Recently I have tries Play-doh which is much softer. It does't give such a detailed model but is much easier to mould and experiment. It also smells better. I would previously then photograph the profiles of the head to transfer to a block of wood to rough cut on the bandsaw. This time I have tries modelling it digitally.

Here is the head modelled in Sculptris, a free cross platform 3D modelling tool that is intuitive and easy to use compared with the alternatives. Next I moved the file into Openscad, an open source 3D programme to add the eye sockets and cavity for the mechanism.

Finally, carved in lime on a Heiz S-720T.
Brass rings have been inserted as an eye gimbal and the eyes are carved from beech wood.
The ahead now needs fine sanding.
Using CNC machinery the whole process is much more accurate than by hand but hand carving is much faster, at least for making only one piece.

Still missing arms.