Yo, I'm not heavily experienced with semi-realism, but I'll do my best to give you something that's actually constructive!
I'll say right off the bat that the pose/composition isn't too original. This isn't an inherently negative thing though; a lot of popular artists are very successful with busts/portraits!
In regards to your painting technique, you seem to already have a grasp on incorporating a decent range of values into your work which is a plus. However, due to the overall soft/blurry and lineless nature of the painting I think some important detail is lost and some areas appear 'too' smooth (making the painting appear flat).
For example, the nosee is almost lost and the skin around her chest and armpit are too blurry to give it a strong sense of depth. The strap across her chest doesn't 'pop' enough IMO as it seems to almost fuse with her skin. The areas with the most depth appear to be her top and the band around her arm.
Switching to her hair, I'd say it's clear enough that I can distinguish between separate 'chunks' or strands which is important, but it could be further improved. Some areas (IMO), particularly the strands that go infront of her shoulder, seem to break the flow of her hair, that is, they appear to curve in unnatural directions. The hair also generally suffers from the excessive 'blurryness'.
The way I'd recommend improving upon this would be to utilize a harder brush for future paintings. In particular, I would focus on creating harder edges on your forms as well as marking harder shadows (e.g. the shadow on the face cast by her hair could be much sharper to give it more depth). Starting out with a pure hard brush and then refining later with blur/blending may serve you well. The reason I suggest this is that having harder brush strokes makes it a LOT easier to give forms depth and to distinguish different parts of the painting. Also, a general piece of advice; keep studying other artists you like, particularly how they paint their shadows and how they balance hardness/softness in their art!
I really hope this C/S is useful to you (I think you've had enough edgy rambling in this comment section from a certain someone : p). ( '_')b