Thank you! I've always been obsessed with character-driven stories and interaction, so I guess this is the result of years of practice and observation, and dismantling stories that do and don't work to see why.
Unfortunately, there isn't a clear way to explain it. It's one of those "you know when you get it right" things, requiring an eye developed over a long time. I will redraw things if I don't feel like I've captured the nuance I wanted to, and a few months later I'll look at it and see where I could have done better. Same with writing. I'm obsessed with pacing and page design, I had a moment of "that's how I think about it too" when Will Eisner described comic panels like music.
The technical approach is I make notes about stories I want to write, then I expand that into outlines, then scripts, then thumbnails, then I draw the comics and colour them and finalise the dialogue. At every stage I'm asking myself if it feels right, if I'm getting across what I want to. That's not to say there aren't surprises and things don't develop organically, but every stage is an attempt to solve as many problems as I can before the next stage. My thumbnails are quite detailed because it makes pencils easier, and I spend a while on them.
I have total aphantasia so I am operating off feeling rather than any mental images. I have no idea how it works and no idea why I pursue this when I'm missing what many visual artists describe as a crucial component. I just do it and I have better things to do (art) than wonder about something I can't change. I don't think it's made me a better or worse artist, though I think it has given me different ways of approaching/developing things. But also, literally everything about you makes your work different to everyone else's work.
You need to care. If your character is into music, listen to that music. If they have an old car that keeps breaking down, read up on common problems for that model. If they work as a film projectionist, watch a training film about using the machine. The characters care about things, have things in their lives that matter, have skills and interests and challenges. If I don't care enough to understand them, why should anyone reading it care, and also why am I writing it if I don't care?
So I do, and in caring I understand them better. This helps me develop characters/story but it also gives me so much more to write/draw. Understanding how things work and how they are done from a physical standpoint makes writing/drawing them easier too. The more you put into your head, the more you can get out later. I'll do way less for a 12 page short than for a 300 page graphic novel, obviously. Pick your battles, a little can go a long way.
They tell artists to collect visual references - solid advice - but you should collect substance too. If you pay attention, you will hear and see things you could never in a million years make up.
I find online socialising difficult, so I go out regularly and talk to people, or just hang around and observe. Chatting with strangers mostly involves listening to them. No one in gay spaces is interested in flirting with me (I'm rather homely and queer men assume I'm straight) but I think an audience is just as appealing sometimes, and maybe even harder to find. You'd be amazed what people will tell you if you're genuinely interested and listening. I once spent forty minutes at a sci-fi con talking to a guy who'd recently gotten into fisting. While I have zero personal desire to partake in that activity (and he had no interest in being fisted by me), I'm engaged, I'm invested, I'm asking questions, spare no detail.
I collect behavior and movement and the ways people interact too. Reading stories on reddit or whatever is one thing, but the words might not be as interesting as the way they're standing, the way their hands move, the way they respond. A guy in a bar once literally humped my leg like a dog because he felt I wasn't paying enough attention to him. I would never think of that as a response to that situation, but he did, and he followed through. Fortunately my friend had just tried to drunkenly sit down and missed the chair, otherwise I would never hear the end of it.
I see the leghumper around sometimes, he's got a boyfriend and avoids making eye contact with me, thank god.
