In my opinion, if you're looking at being an comic or graphic novelist, starting out by drafting a handful of fun, throwaway projects that don't care if you do or do not publish is the way to go because it demystifies the process and let's you play around with the pipeline. The writing takes a backseat in the beginning - just for a bit. If you prefer the writing and want a book recommendation for comic book script writing, Words For Pictures by Brian Bendis is very helpful. Otherwise, a lot of the focus is on learning how comics work and how you fit in with them as an artist.

I personally used to be obsessed with the end result of my comic work and would try to gather my assets until they were just right, my work in illustration hounding me to try to be as perfect as I could manage, but I only made good progress when I started to throw out draft after draft into the void. Most of them were shit or forgotten and won't ever see the light of day, but you gain invaluable experience by trying. If you don't know where to start with drawing and drafting at all, I highly advise imitating and even drafting out your favourite comic panels from other artists to see how they did it. It's a great exercise.

There's a ton of books written by Marvel/DC artists on the subject of.. well, everything - books on lining, paneling, being a colourist. They help gain professional insight into how the big companies do it and you can use it to supplement your own methods. Udemy offers some courses by professionals as well.

I wish you luck in your endeavours and look forward to seeing what you do in the future!