Ear is probably too far out... find the overall shape of the head -- jawline doesn't meet the ear; I think the ear should be bought back in much more, and so you should also push the hair in to accommodate.
Folds of ruff should match up to form of the edges.
Odd you have very saturated outlines for hair, whereas color within is less saturated. Overall, hair could be much cleaner.
Body area also feels a bit too abstract for me... probably due to the sleeves being done very abstractly as well. Folds should have a deeper sense of gravity, they looked to "faked" to me.
I do like the overall graphic sensibility though, really like the green backdrop and where you're going with that.