...And she felt a nightingale left in eternal solitude...
Even if it is not my job and I am self-thought, I always accept criticism on my pictures and I do my best to improving my technical skills and my taste in compositions. Not long ago I've been told that my pictures were not enough expressive. Actually, it would be stupid to suppose that you can be perfect in every single thing you make, but as far as this comment is concerned I have to say that it is something I've always found true - my pictures were not expressive, because I thought that they did not need to be either expressive or emotive, melancholic, ecc... Why? Well, the explanation is not that easy.
My idea about this kind of portraits is that beauty itself doesn't need to be expressive, mind you, a (not necessarily) good-looking girl and a camera are not the only things that will get you to a perfect portrait. You also need a nice location, the right weather, good taste, concentration, ecc... but the most important thing is the relationship you are able to create between you and the sitter. If you know how to make her feeling good and beautiful she will look beautiful, even if you are shooting with your compact camera.
Of course, it will not be enough... and this is the point. Becoming obsessed with perfect composition, perfect pose, perfect girl, ... will just driving you mad, faster and faster. Why? Because perfection doesn't exist. You can aim at perfection, you must aim at perfection, but sometimes people confuse perfection with expressivity. You can focus as long as you like on the composition, but if you don't care about the feelings and the relationship between you and the sitter you will never get even close to an almost-perfect result.