You should be doing all the homework in ink (you can read Uncomfortable's reasoning https://drawabox.com/article/ink). This is to strongly help you in your line work and confidence, especially when moving forward. But I noticed that you weren't able to start in ink, so no worries. Just try redoing them in ink.

In terms on line work, there seems to be a scratchiness and/or wobbliness. When making your mark, ghosting will help you estimate what angle and how far you need to make your mark before making it. Once you've put your pen down to the paper, commit to it as best as you can. This way, you can see if you've over/under shot lines or marked them too high of angles, and moving forward, you will better know how you can adjust.