Okay, I'm not extremely good at critiques, but hopefully I can help you a bit!

Okay, to start off, I must say, well done! The art piece is good, and although there is definitely quite a bit of room for improvement, I think you did well, and will continue to get better!
To start of, I think that the person is a bit too thin. The face is very slender and it has much more of a slope than a normal person would, and the shoulders are very tiny. The neck, I feel, is also a bit too long. But that could be just me.
The face needs a bit more symmetry. The left cheek ends up lower than the right when meeting at the same point horizontally. Make sure to keep the height and length of each side of the face as close to each other as possible.
The inner arms have no start point! Whether is be a girl or a boy, you should always show where the inner arm starts, because that also separates the chest from the limbs. If this drawing went any lower, the person would have one clump as a torso, which I think is quite obvious. Be careful about that!
You should show the neck muscles and the collarbones through the skin. It gives the drawing more of a realistic touch, I think.
If you're going to show the eyes (Or eye, in this case), I recommend you to never cover up the pupil with hair. It could distort the direction that the person is looking, and you could end up with a cross eyed person. Also, judging on the placement of the shown eye, the one you have covered up with hair shouldn't be completely covered. The break between the bang to the right of nose, and the larger bang next to it reveal skin for where the right eye should be. I don't recommend covering up eyes with hair unless you understand perfectly, or good enough, the structure of the face, and the placement of the eyes. On the topic, the eyes are too close together.
The hair is drawn alright, but I think the structure of it is a bit odd. It's alright to have the bangs come of the face, but you should be careful to note how they would fall off. I feel that the bangs on the right side go off the face too much, and I find it weird for it to continue in the same direction it's going in with out some kind of interference, like it was super-glued in that direction. Also, usually, the hair is thicker at the back of the head then in the front. I'm not sure whether this was intentional, but in comparison to the hair on the back and on the front of the head, I feel the amount of hair from the back and the front should be flipped. Again, that may just be me.
The coloring is, once more, alright. I feel that on the skin, it's a bit rough, and that you should smooth is out more. Also be aware of how light and shadow reflect off of a face, and how features like cheek bones and types of noses can effect that. I would recommend using more colors to show the distinctive shadows and highlights on each part of the face, because remember, not everything on the face has the exact amount of shadows and light than the rest. The hair, while the shine is good (But next time make it a bit more noticeable, eh? ), needs more detail. You should show, in each individual strand, the shadowing and light which reflects off of it. As the skin, I would recommend using more colors, both light and dark, to give the hair more texture and depth.

I apologize if I was a bit too harsh, but I sense a talent in you! Just work on those little things, and I'm sure you'll get better in no time! <3

Shape:
• Start with the basic shapes for the head and build it up from there. Eyes aren't proportional to the head, and they're too close toeachother. Try some eyelids. The nose also, could use a bit more detail.For the shoulders, let them become more steeper and wider (just 2 pinches longer than the sides of the hair on each side?) Lastly, try making the neck lines more symmetrical. (chin should bisect the neck)
Color:
• Color is well-done. For the lineart however try using varying pressures (if possible) The shadows seem right, but not really digging the hair shads.. grass-looking imo