I really like the second one. The generally dark background allows the model to stands out. Her expressions is perfect for the atmosphere, too.
The model's face is against the ligh in the third one. Although it could be used effectively in some cases, I don't find it especially needed in that picture. You could have the face/body of the model moves sideways a little to get some light, or you could edit it in photoshop.
The last one is very adorable and the angle is just right. However I find the model's skin tone to be a little unnatural under the lights. I might be wrong because of the screen.
You are doing very well as a beginner. I find it more important to have an eye for aesthetics than the education in photography. The latter you can always make up by studying on your own C:
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Nikon D7000+35mm F/1.8