[SIZE=small]This is long overdo! I promised you this review a while ago, forgive me for my lateness~[/SIZE]
Nio, I've always enjoyed your drawings, your style even though sketchy has a vibe of uniqueness that screams your name.
I think your doing great with characters so far, though I would suggest to work a bit more on your anatomy, especially on the hands and feet, I can see that your struggling with it. Your hands always lack fingers and the arms seem too thin or too straight, even though anime characters have less details and have a very settle tone to their body, they still have curves on their arms and legs defining the muscles.
Good Example of the curves:
I would suggest to practice a bit more with gesture drawing, it allows you to get familiar with the our human body and how the muscles work/curve during different positions.

There is a great website with amazing practice photos as well as a timer and different options to set your exercise. You can find it
HERE[SIZE=small] if you want:[/SIZE]
As for feet, you tend to make them too big and too round, they seem very shapeless.
Here is a good tutorial how to start and define the shape of feet that I would suggest to go over, again though gesture drawing should help you with that as well;
Another thing I would suggest to work on is your color palette, you tend to pick very strong colors, I feel like you focus on very individual aspects of drawing rather than looking at is as whole. I can see that you pick for example a specific color for hair, eyes, skin and so on but don't try to unify them, which results in a picture where everything stands out. Try to maybe put an overlay of a certain color on top of the picture and play with that, it will give a certain tint and unification that you need. Add background to the picture, even a simple one color and play it off the atmosphere that it gives, try to make it so it seems as if characters are really surrounded by that color. It will not only unify your picture but also make it look more polished and finished.

Play with Monochromatic, Analogous and complementary colors, you will be surprise how much of a difference it makes.
Good solid
COLOR THEORY site, I would suggest to visit
I think you got the hang of the human face pretty well, I can see that its one of your strongest points and thats great, you can defiantly draw it from different perspective with a range of emotions~ Kudus to you for that
I like your recent drawings a lot, especially the storyboard, which has a great perspective and usage of contrast.
I also really like that your branching out into more setting like scenes, the commission that you made for Ruby looks spectacular and again the perspective is sublime~
Your ambitiousness and determination toward drawing is admirable, and should be an example for any artist.

I can defiantly see that you have improved throughout the years and this thread is prove of that. Even though you have still a long way a head of you, you accomplished so much in so little time, there is only more improvement and amazing work ahead of you~

I'm looking forward to your next drawings and projects.
Here is a cute cat for ya~: