@tillianisafox if you are going for humans, they have certain proportions that basically apply to ask of them (like ellbows are height of waist, one heads width shoulders etc) - there should be books that deal with this kind of constructions, maybe videos as well. So maybe searching for this specifically helps?
Getting stock poses and starting to figure out the main lines in the body also helps me greatly and improves your way to view things.
@Blahmage the problems for me begin when I try to understand planes/texture and lighting and how does light interact with the shape of the objects and it's pain for me
it's easy to shade cubes or spheres, but it's hard for me to do that with human body/animals because it's hard for me to see them as shapes or break them down in shapes