Stablizers are a bit of a crutch in a lot of ways, and they can hinder learning good techniques.
You can find loads of good tips out there if you search for “line art practice” or whatever, but there’s some basic & useful ones:
Warm up before you start inking. Make two dots, then draw a straight line between them. Do that for a while, and try drawing parallel lines next to them.
Draw three dots and try to join them with an arc.
Draw circles (check them against a template afterwards if you can’t judge a circle by eye). Make circles into spheres with contour lines. Make cylinders.
A decent size tablet is really important, so you can use your arm instead of your wrist. I went with a cheap 6x10” instead of a 3x4.5” wacom, and it made a huge difference.
Looking at your pics, long, clean strokes instead of short hatching is the single biggest thing to make them look awesomer.