Sketch? Please talk about advantages and disadvantages! !

This is a three-quarters female head. First of all, from the composition point of view, the upper part is a little too big, and the head is not completely put into the paper, that is, a part of the head is cut off from the upper part of the paper. This composition method is common in photography and focal plane application, but it is not desirable in the composition of sketch head. It is a failure and I feel like going out. In the future, the composition should be moderate, not too big. There are still some ambiguities in the overall structure, including the turning point of the block surface and the structure of the joint between the corner of the eye and the bridge of the nose. The biggest problem in the whole picture is that the finger smear marks are too heavy after drawing lines. The author wants to make some places vacant, but the vacant area is so large that the whole picture feels weak and lacks hard positive relations. The drawing method of eyebrows should be based on the turning point of brow bone, rather than simply drawing eyebrows, without light and shade, without reality, so we should pay attention to it in the future. However, the overall structure of this sketch is still ok, and it can be seen that there is a certain skill. The connection of mandible, ear and hair, and the covering relationship are all well drawn. Keep working hard and keep summing up, and you will make great progress.