It is a process. I don't think my overall technical capabilities have improved that much since my first try at making the comic, but the knowledge of my tools certainly has.
I would say a lot of trial and error, and going back on your work certainly helps. I don't feel great about my first drafts, but I'll show them to you anyways.
I drew my characters traditionally and colored them on my phone. I was leaning towards the Hellboy looks with big, striking shadows. However, I wanted to try my hand at a more realistic style. Here is my second attempt:
I sent my first drafts to my friends and explained what I was shooting for. Their feedback was the thing that impacted my comic the most. They asked me to change the character's expressions, which wasn't that hard, but it would not work with the current designs. That's why I went for 90s anime.
As for digital art tips, I would advise incorporating flaws into your drawings. Digital art (in my opinion) tends to be too clean, to the point where it looks uncanny and too artificial. Try using textured brushes for the line art (finding and tweaking the ones you like is a whole process), incorporate some grain and chromatic aberration (I like it, but some people might not).
My overall conclusions are:
1. It is a process in which you need to try and tweak several tools to your liking.
2. Ask friends and family for critique and feedback, both the people who make art and those who don't.
3. Incorporate your human flaws into your art. Don't shoot for perfection; perfection is boring.
4. But do try to give your best on each drawing.
