Well I thought I was making progress quickly but you are really taking some big strides in a hurry!
Now I'm no expert but I thought I would give some comments. Something that stood out to me is his hands. You might try making the shadows between his fingers a little darker and deeper. While painting the dark shadow between fingers can look awkward but once everything is done it doesn't standout as much and gives the hands some depth. This could also just be the lighting which can really brighten areas that are shaded well (I think it happened with me a bit on my Long Horn).
One other thing is the skull's eyes. I think they look great but to make them look like they are glowing even more you can make a glaze with some orange (make sure it is pretty thin) and just start glazing around the eye sockets. This will make it look like the glow is casting light out and shinning on the skulls themselves. When doing this make sure each layer is dry before adding another because if the previous layer is too wet you'll start pulling up paint and getting debris. Also by making sure the previous layer is dry you can control how much of a glow you get, you just want a hint of orange on the socket you don't want them to look like they are wearing eye shadow.
Take my advice with a grain of salt as I am still learning. These are just something I have learned from hanging out here and YouTube.
If I am leading him astray someone please correct me.
This is very good though! I can't believe you are already painting eyes and doing a great job at it! They aren't just little black dots!