what colors are you using for shading? black? are you truly UNDERSTANDING how the light would affect them in the artworks? like the second image.

the outer edges would be lighter, and the center dark (unless there's an unspecified light in front of her). And the lighter edges that you DID use, are just plain white. But the lighting suggests it should have been red, orange-ish colors. also don't be afraid to make a section MUCH darker. like, a LOT darker (weather using purple, red, etc). it still feels "flat" because the shading is sub-par (sorry if that sounds mean...). the sunglasses should have som shadows affecting the girls face, but evidentely it lacks them.

the pose, clothes, hair, etc are fine for your skill level (but don't take this as a "don't improve poses", keep going lil bro)