>>3140798By learning the structure. The other anon that mentioned drawing from life is a great place to start.
Loomis is a good place, but his anatomy book is a little moderate. At least it's not the beginner stuff you should be aiming for. Having A Pencil And Drawing For Fuck's Sake (I forgot the title) is one you should be going through despite it being boring. If you breeze through it, fine, you went through it. Successful Drawing is another one in line with what
>>3143409 posted. A valuable thing to center on is being able to, like life drawing anon said, representing 3D in 2D. Perspective is /very/ important and will help immensely.
That being said, what you see in your original picture is very simplistic once you can break down what you're looking at into shapes.
You should be able to reproduce this stuff, to a point. More so if drawing like this is your aim. If you can draw from life and learn basic anatomy after you've learned to represent 3D in a flattened surface, then drawing this fella will be easy.
Anyway... The final point is, "reproducing" is your aim but copying isn't. Draw your own original pose, set piece or whatever, and reference the image you have to make it more accurate.
It will look like shit, probably. So you look for where you fucked up, try drawing your own again, and keep doing it. That's reproducing and learning the fundamentals will help with that.