A tutorial of sorts, although these are all probably stuff everyone knows :I
This is pretty much how most of my sketches are done for now, and the beginning steps I generally and currently take on the complicated drawings, after I made all of this I always blend all the steps in one layer and start patiently detailing the whole thing, which includes adding other colors to the mix or correcting any mistake I always make.
A few optional steps that I could take to keep going with these, but weren’t necessary in this paticular case, would be to add a layer to add some stronger light spots (useful for metal and making some shiny skin bits, among other things) which can be done my making with a layer set on luminosity (the closest on PS would probably be color dodge) with 50% transparency; and then coloring the lineart, which is done by creating a new layer above the lineart layer and then make a clipping mask (like what I explain on the 4th step).
STILL, I would recommend that you take a look at others tutorials until you find a workflow you feel comfortable with. HOPE THIS HELPS!