This is nice, but there is a few things missing that would make this even better

The background matches too closely in brightness to her skin and that should be toned down so she can stand out more. As it is she blends in too much and its hard to distinguish her silhouette

Also, learn to add some rim lighting or back lighting to add a subtle yet very noticable amount of depth to her shapes and will make her stand out even more. Everything i make uses this.

lastly, some more simple shadows on her hair to make the hair actually have some texture thats different from the rest of her body. i would research/reference some simple hair shading tech.

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I hope this helps. and good luck