Hi there :) I think you've correctly identified one of the tools you can use to make us feel how far the mountains are: atmospheric perspective, aka why you colored your mountains with low contrast: Indeed, with distance, things get blurry and bluish and less contrast is apparent. However the fact that you kept the line work around the mountains sort of cancels that effect. Maybe it would be worth removing all your black contour lines, and not to add any texture to the mountains (keep em somewhat blurry). You can also add contrast in the foreground, for example by making the closest part of the valley darker, and gradually losing contrast in the distance. Good luck!

I decided to give this a try. I had trouble with figuring out the muscles from the other muscles of the arm when they're not visible. Am I supposed to imagine them, or am I supposed to use a model to find the muscles I don't see? I have a little ecroche model that I try to use. Am I supposed to do that? Any feedback or help is welcome.

Another forearm drawing. CC is appreciated.

I feel like an important part of keeping the passion alive is to save some play time and have fun with your art, no matter how bad it may look to you. It is especially important to cultivate that because as you improve, your critic sense will too and you might feel like your art is never good enough. Cultivate having fun with it sometimes. Notice not only the flaws but also what went right, what you are good at. Learn to be patient with your progress and enjoy the process! Those are skills too :) Good luck

I actually think you're doing quite alright with pelvis position, so just keep doing that! Here are a few thoughts about what's confusing when drawing the simplified pelvis. So, what you are supposed to do first is read the bony landmarks and that tells you about the pelvis position. It gets a bit tricky when drawing it simplified as a bucket or a box though because it is not the pelvis exact shapes and people interpretations can vary. Some will use the box and include the great trochanter (a landmark on the femur) in it. Some will make the bucket go below the genitals, as to include the ischial bones, but others will stop at the pubic symphysis since the ischiums are buried in muscles and never visible. Some will make the box or bucket go as high as the pelvis highest points (the iliac crests) while others cut it at the sacrum and iliac spine heights, and will add a bit more heights when adding the iliac crests. Don't panic, you don't need to know all these details right away! Using the simplified pelvis is much more important to develop a feel for its position. What I am trying to explain is that there is not one single approach to simplifying the pelvis and you just... have to feel your way in placing it by doing exactly what you're doing and doing it a lot. You coud also try drawing the pelvis as a box, which clarifies front and side plane more. Sorry about the lengthy answer, haha, pelvis are hard!

It's not a matter of choosing which is better in absolute terms, it's a matter of knowing what your goals are and which aspects you need to work on to get there. Anatomy with lines makes it easier to study gesture and to design clear shapes. Anatomy with light and shadows helps you to feel the volumes more and makes you better at rendering. When in doubt about what you need, like James said, a bit of both is good!

I would advise you to find and study Scott Robertson book "How to draw" to understand more about perspective. If I am to provide a quick tip for you to understand circles in persp a bit more though, it would be to draw first a box that feels right to you, then freehand or construct ellipses into it. There's a lot more to this so again, you'll need some books to be more precise or understand what's going on. Good luck!

Depends on your goals... where do you wanna go with your art?

Hey Tony, I'd say find some art parents, as Marshall likes to call them https://www.youtube.com/watch?v=vxJOjvsj3j0 : People whose style you like and will inspire you to start making your own stylization too. You can even study an artist by trying to do a new painting in their style (not copying one of their painting but working on a new subject and doing your best to make it look like their work). This, obviously, is for studying purpose only, as you don't really want to become a clone of any one artist. Doing this exercise multiple times with a good variety of artists will lead you to think and come up with your own mix of stylistic choices.