Your work is strong. You have the good habit of doing clean edges, that speaks of confidence. It's precisely what an art director wants to see. I particularly like the girl with dragons piece, you got crisp light and shadows there!
Is there still time to do some critique? In some pieces your detail level transitions are too steep; they feel jarring. It's like if you enjoyed painting your favourite parts then got bored with the rest, so you just sketch the volume without quite following through with it. You can easily make your work stronger by working these transitions more carefully.
You can instantly increase the level of detail of an area working one or more of these: volume, light, cast shadows, material, reflections/glossiness.
Sometimes all you need to do is follow the lead of an area you worked. You worked the volume and light of her face. To create a softer transition you can work the volume and light (in this case reflections) of her hair, but with bigger brushes. Then, on her arms/body you can drop the LOD by following through with the light you indicated on her hands/face, and doing only little volume. On her dress you can keep decreasing the detail by working the light only where its absence would be jarring, and volume as well. You can push the detail up by working the material instead (translucency at edges).
Another tip: Be careful with your brushwork when it comes to perspective. Your snow piece feels inconsistent because the brushstrokes on the ground aren't describing anything. The most noticeable characteristic of the ground would be its perspective, thus that's what the brushstrokes should represent. We can also see too much of red's footsteps and the trail behind him/her, making the scene look skewed. To work perspective with your brushwork pick the direction that better describes the shape of what you're painting, and when it's not enough, literally put the brushstroke in perspective.(stole example from another critique I did. Shhh.)
Also a random tip: You can do vignette through hue+value change. Sometimes when you use value alone it reads as volume change or feels muddy.
Keep up with the good work, and don't forget to link your portfolio here when you're done!