Lighting, composition and focus. Avoid centred subjects, use reflectors and/orfill flash to avoid the problem you have here of too-bright highlights on the right side of her face and too-deep shadows on the left; not the extreme 'raccoon eye' she has. Avoid having patterns like the boards in the background; they draw the eye away from the subject, and don't forget to level your images in post. That aside, it's a good start! Keep shooting.
Just my $00.02 worth - your mileage may vary.
~John