lots and lots of hard work and drawing, and researching (looking at people, or whatever you are drawing, you will always see something knew, for people and animals learning anatomy) most importantly learning how to draw shapes, if you can't draw shapes start there, cause everything is just made up of shapes, start with lines circles, ovals, squares whatever, just start. this is the advice I wish I would actually follow XD but yeah just learn about drawing, do a course in it if you really want to, or do life drawing, just do something.
O and learn the different types of shadows, one thing I really like about this artwork that makes it look 1000 times better is that the artist is actually shading properly and you can see the types, the main are cast shadows (basically shade) then you have form shadows (shadows caused by shape) and what I would line shadow, which is really just form shadow, but it looks like a line (like the underboob in the photos being a dark line), now there might actually be a proper third type I don't remember, but the first two are need to know, cause you see so many artists only doing form shadows and it just looks wrong and uncanny but unless you know you just get a weird feeling of something doesn't look right.
