lineart tutHey Rin I found this tutorial to be pretty damn amazing , I know your doing portrait but I never even thought about add as many guidelines and to this extend when drawing with my tablet... when it works... anyways this is a pretty good way to increase your skill, there's also a tutorial on doing flats, and coloring by the same author just look in their previous works stuff.
As for my opinion, I like the coloring but I hate the lines, they look extremely weak and messy, go get solid black lines in after your done drawing it before you start doing the colors... the right shoulder needs to be slightly more slanted... actually the more I look at it, you got a 3/4th face and a portrait torso... you got to change either the necks form and positioning or switch the torso and shoulders a bit more, either way the neck looks like it needs work as we all hear ya...
I enjoy the fact you didn't use pure black for the facial tattoo.. keep it up, I need practice as well.. now only if my tablet wasn't broken XD