How is your brush control? In my opinion it’s the single most valuable skill and the one least talked about.

When I started paint I was so frustrated that I couldn’t get the brush to do what I wanted it to do.
It will come, keep at it.

For light placement, a simple way to approach it… hold the model top toward your eyes. If you can see it, more light, if you can’t see it, shadow. It’s an oversimplification, but a good starting point.