Okay. So before I discuss the places to improve, I want to talk about the wins - The Apple or Sphere in her hand has excellent sheen and the dots add interest/the Leaves look authentic/hair texture for the most part looks good/ and the makeup's coloring and blending was done well/ chosen backround and dots out of eyes was a fantastic touch. As well as making sure not to choose a boring black for the hair etc.
>>However, I took a few looks back and forth to the reference and your work and I noticed everywhere besides the hands are much flatter than the original, your structure is off in places, and the hair could use depth too. *But you could fix structure in the future by measuring things out, doing an under-drawing with a light drawing medium (with a grid or to satisfaction) and then painting outlines over the lines with a dark color. Then you can see where it isn't accurate or where you want the dark areas to show up - in this piece the armpit/arm edge areas are where you should have had edges recede (giving you curves). *Which leads me to the next point - don't be afraid to put in dark areas that recede, and make sure your mid tones are distinct. The original does seem kind of flat in some areas, but if you look closer, you see places where there are allowance for highlights (For instance in the forehead) because of the slight mid-tones at each side that tell us the forehead is round. I think the biggest place where you leave it to bright pale tones is around the nose, down to the lips. Here we don't feel how the cheeks come forward, where the sides of the mouth should recede. The lips and nose seem okay but they fail without the area in between being given a chance for depth. At the end of the day you need to make your value range much more extreme where necessary (the neck in the original is Much darker), but also ranged (the sides of the cheeks should have more shadow and width for good cheek-bones) and soft in the areas that aren't (subtle, but Noticeable face structure) but still rise and fall.
*Lastly, though you largely have the right idea about the hair, you still missed how the groups of strands come forward and recede in the original>>> *only in the main portion. This is harder to describe from memory, but think about the hair is separate pieces that snake over and under each other - not as one united piece. You did this at the top but even there, you cant allow that piece that rounds over to be so exact and stiff. This is why it would help to do an under-drawing; since you'll be drawing out each piece and individually and see all of the sub-groups that you're missing from your reference or any hair; don't under estimate subtle waves.