Im worried about people looking at your references and getting hung up on making the gradients of the light and shadow perfect and pretty and having them actually fail at understanding the shapes they create.
New artists have issues understanding how to make shapes look real. What you draw might look real to you because you made it but you don't understand how things actually look. To make things look real do your drawings need to have depth. What depth means more or less is making something look like its 3-d, that it isn't all flat like in parappa the rappa or south park.
1. To do this you must first be able to draw simple shapes in 3-d, from
2.Step two is to be able to combine those shapes, and bend them if you cant, you cant go to the next step.
3.Step three starts getting complicated because you need to apply the rules of the human body to combine the shapes in a way that look like the way a human is formed. Humans are formed in a very specific way and have proportions and joints and funny little limbs. It helps if you think of it like you are drawing a robot.
4.Being able to see shapes in 3-d without having to draw in the cones and squares and cylinders that you used to have to do to draw it right with depth, you can apply anatomy and all sorts of neat things like light and shadow to make your drawings look really good, and have the forms underneath make sense! BUT sometimes artists need to do this anyways to get what they are drawing perfect in perspective and stuff, so the things you learned before stay with you and you use them for as long as you draw!
Shout out to Bizarro Joe, Rogue Soul and Master Merol for the great examples.