R: So now I have a sense of your current skill level with your eye and how much you've observed. You've done well on capturing the overall silhouette, but as you can see... it's a bit distorted. You made her more midget'y in appearance, as Joel drew her with a longer proportion. Also, note your face placement. That shows that you need to work on observation more with the proportions in the face. Your eyes are further apart, as Joel shows a simplified version of actual facial proportion. There's room for the side of her face on his; on yours, her right eye is a bit too close to her ear, showing little evidence of the plane that is the side of the face.

Also, look at the way he drew her right arm deeply and compare it with yours. Yours is missing her elbow, and her upper arm is a bit stunted as well. But that's where anatomy studies will prove valuable for you, and that's why I keep saying, anatomy practice is a must. But when you practice, you have to really look at what you're drawing and studying and observe it deeply; break it down, etc. 'Cuz his style looks simple, but in actuality, it isn't. But it's believable because he has a very well-grounded understanding of how anatomy works, even though it's simplified in some cases, like this pic.

K: So... lots of practice. It was driving me bonkers too. Because I saw some of the problems... noticed some things just didn't look right, but had no idea what the hell to do.
R: LOTS AND LOTS AND LOTS, MAN. I think people underestimate how much you should practice. You have to be a madman. Not just a few lil' doodles here and there. But dissecting limbs, muscles, shapes, forms, putting them together, taking them apart, etc. That's why they always say, "learn the human figure first, THEN you can pretty much adjust your style to any kinda style you prefer afterwards".

But for now, you have to work on capturing an accurate silhouette and overall body proportion. 'Cuz it's no point learning anatomy if certain parts are shorter than they actually are and your eye distorts things. You have to get the overall shape down first. 

So now, your next try is to draw this again, BUT only draw the overall shape of her. No details, just different organic shapes that match her in proportion, then let's see how close you get. Try to get it as close as possible to her outline. This is all eye training. When I get done with you, you're going to start seeing things in a whole new light LOL.

K: So again, as a silhouette?
R: Yup, draw it again. But work on her shapes. Make up shapes. Doesn't have to be just an "outline drawing" or contour. The shapes you come up with should match her actual silhouette.
K: Okay, I understand. I'll dive in then. 
R: An no cheating, fam. LOL
K: Hahaha, nah. I'll be only hurting myself. 
R: Good mindset.