Well, for starters - if all the yellow thing is light, you should more think about where it comes from, aka source, and then put it only on relevant places.
The angle of the lower jaw seems to be out of perspective.
Depending on the perspective, the head spikes seems to be behind the head.
But At first place, I'd recommend you to take a normal pencil and paper and train the boring way sketch tons pictures every day. It'll make your line less scattered. Also, without using a rubber, it'll teach you to think about what you want to draw. To train shades and lights, simply draw normal objects you have on your table, using your lamp to put the source of light.
Anyway! Keep the drawing up, because if you will, you'll get better with every picture. Don't give up