This is a very well executed portrait of a very pretty subject. I love the finish you have achieved with the skin. The skin is very realistic , the effort you have placed in the eyes is quality, not just the blue eyes but the detail you have placed into the eye lids and lower eye lashes, they almost look as if you have lifted them off a photograph. The mouth area, again you have captured the look and visual feel of soft lips with a lovely almost mischievous smile! Her nose is nicely drawn ( it would be nice to include link to your reference photo).
The next thing I picked up on is the catch lights in the eyes you may want to try a Square catch light and you slitly curve the square to the contour of the eyeball, this technique is becoming very popular, have a look at some professional photographers work done in studio you will see what I am on about. Also you use of high lighting areas of the skin is well done and again this can make or break a portrait hence being able to view the reference picture as we are not familiar with your subject!
You have done the earring in my opinion you should have put a little more detail, bit sparkle. The reason I am saying this is because in the picture is a high light area simply because she has exposed them to the viewer! As I said my opinion.
The hair, this is difficult to do but you have a lot of free reign as hair is never in the same place from one day to the next, unless the subject has a crew cut!
Now this is my pet hate so stick with me. Where the hair meets the blue back ground you can see the dark line you have used to mark out the canvas! Never in real life will you see a person with a dark line around them! What I would suggest is the hair line against the sky should be a smooth gentle transfer. Either paint over the line or don't use as much pressure when drawing the rough out. When you did the hair did you do it last I wonder! I am looking at he right cheek as you look at the work. It is well worth doing the hair first then do the face, do the opposite when the hair falls over the face, you will find it is a technique that will make you enjoy the work even more...
Finally the neck line. I think if you had allowed this to fade away or include some of the clothing if you want a Dead Stop where the skin meets the cloth.
On the whole his is really good work and it borders on photo realism! If that is what you are after achieving then you are knocking on the door.
As I said earlier this is purely My Opinion! And you should take from it what you want. I like this work you do and what I have identified is what I think you need to tweak in order to move onto the next level with your work.
Thanks very much for your thoughtful comments. I always enjoy getting feedback like this and agree with the points you make.
I was mostly concerned with the skin/eye highlights and didn't really know what to do with the hair and neck outline. I was trying for more of a stylized Drew Struzan look, but I can see what you mean when you say a smoother transition would be more realistic.
Thanks again for taking the time to critique and offer your advice!
Your welcome and hope you can take something from my observation to help you and as I say it's only My opinion. I was given a little gem of advice years ago and it improved my work no end, it had nothing to do with technique etc, I was told take all the time you need to finish the work if you work to a dead line you will make more mistakes, miss details and it will look wrong. I took this on board and started taking time on my work. I have been know to spend upto 200 hours on just one piece, I used to rush work just to get it finished rather than put it down and go back to it later.
It's a little pointer that changed the quality of my work for the best.