OK, so I'll do a brief, point-by-point critique here.
Again, though, I really think you should take the time to look at your work again. Having people tell you what to work on can only go so far - the key is to train yourself to notice these things on your own, that way, you can fix your work as you're drawing, and have the results come out really well.
EYES
mentioned the eyeball thing earlier. The space between the eyes is pretty solid, so I wouldn't worry about that.
- The irises on Reference Sakura (Ref) are, again, maybe about fifty percent of the eye; the rest is white. The irises on Samantha Sakura (Sam) are much larger; perhaps as much as 80% of the eye, leaving very little white.
- Anime eyes tend to be big, and people tend to overestimate the size of irises anyways. Not an uncommon mistake!
- I'd pull the size of your irises down.
- Also, if you notice, the roundness of the irises? On Ref, you can see about 80% of the circle; noticeably, on the lefthand iris, you can see an inward curve on the upper left AND upper right.
- On Sam, you see maybe 60% of the circle, and it's all outward curves.
- I'd pull your left iris in quite a bit, on both the left and the right, and make sure to get that inward curve. The right iris isn't quite as wonky, but that's partially because you've got that weird hair thing going on, which is completely offmodel (more on that later).
the (left) pupil and highlight should be a little bit smaller, too, and the highlights need to be a raised slightly on both sides.
NOSE
Ref's nose has four elements: the upper line of her nose, the lower line of her nose, the nostril, and the shading.
- The upper line on Ref is fairly long; if you include the shading, it's about two eyeball height's long, starting at the top of her eyeball and extending one eyeball height below the lower eyeline (the solid line, itself, however, is shorter, and starts a bit over halfway up her eyeball; in line with her pupils).
- On Sam, the shading is absent, and the main line starts at the top of her eyeball, extending only as far as the lower line of her eyeball.
- Obviously, what you've have to do here is extend the upper line of her nose down more, paying attention to where the curve is. The uppermost section of Sam's upper nose line could be dropped down, or left as is; see how it looks after you're done.
- The lower line on Ref is all about the angle. The upper stroke is in line with the upper line of her nose; the lower stroke is considerably longer, and at an oblique angle from the upper stroke. There is a slight curve near the end, but you can probably ignore that safely.
- With Sam's lower nose line, both of your strokes are almost the same length. They're also angled too sharply. You've drawn her lower nose as a triangle, when in fact it's more like a bent hockeystick. You also need to shift it over more, keeping it in line the upper nose line (it should at no point cross directly below your right eyeball; making a vertical grid line might help you).
- As for the nostril and the shading, you didn't do the shading, so skip that! And the nostril
- Ref's nostril is below the midpoint of the lower stroke of the lower nose (sorry, hope that makes sense!), and is located in line with the rightmost hair of her eyebrow.
- Sam's nostril (I think that's what it is?) is much too high up vertically. The horizontal position may be OK, I'm not sure, but you'll definitely need to fix the eyebrow.
Other quick points:
the neck stands out; definitely check where you're drawing her neck and chin. Her neck lines should be on either side of her chin, and her chin needs to be dragged leftwards quite a bit (keep it to the left of her nostril.
But the BIG THING is her hair. Anime characters are pretty generic in so far as the basic model goes, which means that hairstyles are really critical, as hairstyles are often the main clue to tell one character from another.
I really don't know what happened with you and her hair, because in the early parts of your sketch, you were almost getting it:
but somewhere along the line, you went completely off reservation.
I'd redo the entire hair from scratch, before anything else. Even if you leave the rest of the piece as-is, I think if you get the hair even slightly correct, you'll find that Sam "reads as Sakura" FAR better than she does now.
Again, really look at the hair; notice how it consists of an M shaped bang in the middle (hair strands drop to the eyes, midpoint is above the nose), then it's got a straight, slightly spiky, shoulder-length bob coming out the sides. Hairband on top, nestled behind the front hair section, dividing her rearbob and forebob into distinct sections. Take it one step at a time, and don't be afraid to re-evaluate as you go.
Right now? I would not know that your finished drawing is Sakura unless you told me. But get the M bang, the spikey bob, and the hair band in place, and I think it'll come together.
-edit- if it helps, here's your piece overlaid on the original. I rescaled it to keep the eye sizes as close as possible.
As you can see, the irises are too big/mishapen, you need a little more white in the eyes, the nose is out of place, and the mouth is being dragged along for the ride (probably because you were trying to get it between the nose and chin). The neck is actually OK if you keep the eyes in the same spot and pull her lower face leftward, but the biggest problems are the chin, which is throwing off that whole lower face, and the hair, which is totally incorrect and hurts the whole piece. You need to redraw the hair (and don't forget to pull it up further, too, foreheads can often be tricky! We think we know what a forehead looks like, until we try to draw one...)
