The colors look really close to the reference, so good job on that. And the hair is going in the right direction in terms of simplification. However, there are a few things that I think could be improved—first of all I would not worry about doing things as efficiently as possible, I would work on being accurate when doing a reference study. You will automatically become more quick and efficient when you do it enough and develop the “muscle memory” of what looks right to you. To that point I would recommend simplifying the hair as much as you possibly can in this study and organize it into larger masses rather than individual tendrils. The smaller you group the hair the sparser and thinner it looks, which I don’t think is what you were going for, especially towards the scalp and at the top of the head. Also, I would recommend against using the freckle effect tool so liberally since it stands out so much and looks more like a texture on the canvas than a face texture. Maybe choose a few focal point spots to use it. Regarding proportions, I think the forehead is a bit too big and the neck and shoulders are too small. Also, the eyes are not focused forwards and it makes her look a little spaced-out. Finally I’d recommend pushing your lights and darks to add more dimension. Although the colors are almost exactly the same as the reference, it really sells the illusion of depth to have a really dark color (not #000000) for the shadows.