Doodles on Envelopes

These are some doodles I made on old mail envelopes, while listening to music, and looking at images on google.
I still prefer pencil and soft eraser as medium to make drawings, because they offer the best way to gradually form shadow and light.
On my channel I'm posting mainly digital art made with an Art Tablet, but I'm still struggling with shadowing , it looks still too abrupt to me, though I think scanning pencil drawing gives kind of a dull image of the illustration and it's not very eyecatching for the internet.