Since you took the time to critique my work I though I'd do the same for you c: I don't know your tablet type, I've only ever worked with wacom's tablets, but it looks like you're getting the hang of it (great second go on your hue/ saturation shifting on the last image, it's a clear improvement on your first. It's been a pain in the backside for everyone haha).
On the Discord channel's Resources topic someone posted an elaborated version of the pen lines assignment, I just found it myself and I think it'll really help improve your pen control, so maybe give that a shot? It can't hurt either way c:
Thanks again for critiquing me!