the honest answer is a lot of self-teaching and practice at my main interest.

but if you're looking for practical advice:

learn and become comfortable with perspective. As in, the 1p, 2p, 3p grids and how to orient objects in them. Full stop. I know a lot of artists naturally avoid learning it - it's literally the #1 requested skill goal I'm requested to teach among all my clientelle - because it is essentially digital math and highly structured, but having a strong understanding of basic 101 perspective removes basically 90% of guessing and trail-and-error artists tend to do.

training your eye to understand depth of field and have a logical understanding of angling shapes is clutch, it's the majority of the work that goes into becoming comfortable with bodies. once you have that down, you can do a lot of things casually, like making your anatomy looking solid and taking up a sense of space by controlling sense of weight and mass. It becomes much more intuitive to understand how to simplify muscle/body shapes and how to orient them. And it's also a lot easier to logic out foreshortening, which I'm convinced is only a struggle for a lot of artists because they're guessing blindly at a sense of perspective they don't know how to see or understand.

I hope that was helpful and thank you very much for the kind words.