For the line art there are many different ways to do it, and know that I am no expert. But a few rules is you want thicker darker lines for the sillhoete and also when objects are overlapping others and it looks like you have the right idea. I find working specifically on line art really difficult to improve as its kind of a symptom of getting better at other skills. At least thats how it feels for me. As I understand shading and volumes more it makes more sense where to place emphasis. So I was like you I wanted to study how to make better line art but I think for me at least it just levels up as I get better. Not sure if that is helpful but you did a good job here!
