Oh god, sorry this is such a late response. I forgot the password to this thing, so I haven't been getting notifs for questions!!

I have a lot of trouble being "studious", in the traditional sense, so it's very rare for me to sit down and grind out something over and over. Usually I will look to my Bridgeman copy for details or Morpho/Micheal Hampton PDFs for shape breakdowns. I think you can learn stuff from all different sorts of places, and I try to understand each artist's method, if that makes sense. I also find when I'm looking to improve a particular body part, I'll start honing in on that part when I'm consuming other people's art, too, because there have been several times where I'll see an artwork with a particular shorthand/shape language for that part that makes all the anatomy study suddenly 'click', like AH!!!! I GET IT NOW!!!! So it's important to always be looking at other people's art and trying to reverse engineer it, and develop a sense of appeal while you're still developing your anatomical understanding!

If I'm really, really stuck, I'll use a reference like Posemaniacs to determine things like muscular order, what certain muscles look like in perspective/from weird angles, and if I'm MEGA STUCK or it's just not working, I'll try to find photo references. This is mostly preference because a) finding references is so painful when looking for non-standard poses and angles (not to mention lighting and contrast) and b) I've always wanted my art to be more gesturally based to begin with, and drawing from photo reference really heavily in the learning stage (in my opinion) tends to lead to really stiff figures.

Overall the process is attempt > observe (other artists) > study > observe some more > re-attempt > reflect and repeat if necessary. I feel like it's important to try something again completely rather than try to 'fix' it. Fewer studies while being tuned in and thinking hard is much better than trying to draw 100 pelvises from reference without thinking about anything else other than copying it down the 'right' way, I think.

In terms of resources, here's some books:
Morpho: Anatomy for Artists, Simplified Forms, Joint Forms and Muscular Functions, and Skeleton and Bone Reference Points;
Michael Hampton's Figure Drawing, Design and Invention;
As for Bridgeman, I have a copy of Constructive Anatomy, but Complete Guide to Drawing From Life is very good too. I'd recommend The Human Machine but I have never found a scan that didn't look like complete shit, so if you can find a print copy for cheap or at a library it might be useful.

I don't watch videos a lot, but I find Roberto Osti's videos to be very detailed and informative on how to develop anatomical drawings. I learnt a lot from his inner leg and crotch videos!

Oh and if you're gonna study from photos, I find yoga pics/videos are good for understanding muscle torque/movements and how different body parts move against one another.

sorry about the ramble lol. Hope it's helpful!!

It's funny, I think the Teen Girl is really hard to pull off in a way that's interesting... I tend to find lower/early teen girls more compelling, just tend to have more interesting stories I guess. Seems when writers try to tackle older teen girls they end up just being Woman Lite. I loved Ellie in TLOU (the original), liked Sasha in Amphibia (these 2 for very different reasons LOL), I like a girl to be a bit rough around the edges. I find the generic 'alpha' girl annoying though, same with the generic tomboy girl. Don't get me wrong, anon, I love tomboys on principle, but I like it when the masculine energy shines through naturally. It's more elegant.