Lots of progress here after the face was done -- and of course the pink hair was a blast to paint.
One thing to note about adding the background after the subject; it's not ideal. You can see that even in the last two shots above, that adding the darker background immediately made the figure have less contrast. darks look less dark, lights look less light. it's a good reminder that values are relative. Thankfully, I've done this so many times that I fully expect to tweak values once the background is done; I don't worry too much about my darkest darks and lightest lights when i'm doing the initial painting.
I generally glaze in two different steps: darks and lights. I use Liquin for darks, letting each pass dry in between. Liquin dries within 24 hrs so it makes multiple passes on dark areas a little quicker. It can still be a little tedious, but gradually pushing areas darker always looks better to me than going in and trying to darken it all the way at once. it lends a little more depth, and allows me to control the color temp a little better. adding blacks and blues can tend to cool an area off too much, especially in shadows (which tend to be warm) so instead I add some combination of trans oxide brown, perylene red, alizarin, black and blue over a few layers. I also almost always use a clean/dry synthetic brush to soften the glaze, dial it back a bit, and/or remove any brush strokes.
In the image above (right side), I haven't oiled out the dry paint, so you can clearly see the areas I've glazed in the glare. Liquin is extra shiny when it goes down so it also makes it easier to see just how dark the colors are.
When the darks are where I want them to be and everything is dry enough, I'll start working lights. thin coats of light colors don't look as good to me. lights generally should be thicker (to add to depth) and I've found that thin coats of too light a value tend to look almost smokey. so instead of using pigment mixed with Liquin to glaze, I'll give the majority of the piece a very light coat of Oleogel to bring everything back and create a soft cushion. then I'll go in with lights without thinning them at all on the pallet. I'll mix colors, then go directly into the Oleogel on the surface, which will thin and gain a little transparency. I'll generally spend a session or two getting the lights where I need them, by building up lights as I did darks - but instead of keeping things transparent, I'm actively trying to get less transparent and thicker the lighter the color gets. for highlights (generally the lightest part of the painting, in this case the tip of the nose) I'll try and get a bit of impasto going -- either with more paint, or the addition of an impasto medium (I use the Rublev Impasto medium when I need it).
I'll get a final pic up soon. leave any questions in the comments -- I'm happy to answer them. hope this was all helpful and that my freestyle punctuation and run-on sentences wasn't too annoying.