Never fear, your local artist without an artist title is here! Now gimme a bit to point out some things of improvements to help you along your way of becoming an anime master! (which sucks because your better at shading than me D: )
YUYU COMMENTARY WITH PICTURE EDIT WITH HELPFULNESS INCOMMING (LOTS TO READ)
http://i288.photobucket.com/albums/ll181/shinypachirisu/rin_kaenbyou_by_glimmeryleaf9-d599x3u.pngOk hers some helpfulness. Theirs actually nothing wrong with her neck in my opinion. (I draw necks like that) but it you wana make it nicer, dont shrink it, make it a little bit wider, and its perfect. The head looks a bit alien like for one reason, her mouth is off. And yah, one little thing like that can throw an entire face off. you see, you know how fave jaws when drawn in anime are like a V, then two lines up, indenting a little, then half a circle for the top of the head? Right where the V stops is where the mouth is saposd to be. Or at least thats what ive noticed recently. Yours is....right at the eyes :V so she totally has an alien like face. I draw some blue lines for a common anime face and did a yellow mouth where it should be, and it looks right to me. Also on the side I gave you two references, one of your style kinda, with the indent more lined up, and one of mine.
Ill even link you some images where the mouth is done this way, and looks accurate, so you can see what I mean
http://browse.deviantart.com/?qh=§ion=&q=anime#/dfjv4zhttp://browse.deviantart.com/?qh=§ion=&q=anime#/d4srtjihttp://browse.deviantart.com/?order=9&q=anime&offset=24#/d18vd5a(also note, if the mouth is open, you line up the top of the mouth, not the middle, as seen in image 3)
(on a side side note, the distance between the mouth and the eyes determines the age of a character, which is why chibis have a VERY wide jaw, that lowers the mouth, and they usually lower the eyes two, so their practically toughing, making them look younger.)
I also took the liberty of analyzing your body proportions on your character. (where the circles are is where the knees should be) the arms look a tad long so if your legs on your picture are longer than I think (knees are lower) its fine dont change a thing.
Now with the also comment on the stiff hair, I see it too. your biggest problem here is her dress is all flowy and gorgeous, but her hair keeps a perfect shape. Make it flow with the wind. And DO NOT have them in the same shape if they wind is affecting them.
As with her stick arms, I drew something for that too!
arms are kinda like legs in my opinion (what no they arnt! Going straight to the little image I draw cause the one I drew on her arm is a tad off, an arm has this thing called fat. fat is affected by gravity. So when you make their arms out-dent, do it at the bottom of the arm. have it come in at the wrist. Have the part above the elbow a little thicker. (not all slender, thats for lower arm) have the top part of the arms have only slight curves, while the bottom ones are more dramatic. And have the bottom lower arm fat be more towards the elbow, KINDA LIKE A LEG.
Ok, thats my version of help (never done this before) so I hope it helps and I hope you dont kill me for drawing on your picture :V