Basically what others have said.. The biggest thing that jumped out at me was the lighting and shadows. The first two could have used either a very very light fill flash or a reflector to lighten up the shadows on her. Their third one needed a lot of fill flash or additional lighting from somewhere to lighten up that shade. What lens where you shooting with? Like others have said the horizion is not level but I also noticed it looks a bit curved (aka wide lens). If possible you might try shooting at 50mm (or equivalent for your digital) to make the horizon more of a straight line.