First, I must compliment the photographer on the use of angles and choice of lighting conditions in this composition. Setting the composition at a slight angle creates interesting diagonals in the composition; between the angles of the model and window braces in particular. The position of the model slightly off from center also draws the eye around the entire composition rather than to a specific point or straight off the photograph. The choice of natural lighting from a single source helps draw the focus of the composition to the model. Having a tinted or partially covered window also prevents excess glair or high contrast between lighting and shadow; the lighting used gives a nice, subtle feel to the composition. The model is also seated in an interesting pose, making the composition more balanced in this shallow depth of field.
Some things to consider would be the area around the model; do the additional textures and surfaces add to or clutter the image. Second, try experimenting with various cameras, lenses, settings, and depth of field; the model's mid-section and face are in perfect focus, though her feet (the title focus) are slightly out of focus. The setting of the room can also make the space seem more open/vacant or cozy/crowded (it all depends on the photographer's intent). Finally, try experimenting with lighting in the various spaces of choice; lamps with various bulbs, heights, and direct or indirect lamp shades (if any). Mirrors can also add subtle light from the windows. The windows themselves, from the direction of light (time of day) to how much light is entering the room can both add to or take away from the composition.
In all, great choices in the composition. The facial expression and position of the model leaning against the window (as well as the choice of how her hair drapes down across her shoulder and toward the front, keeping her face clear) make the composition very interesting. Taking into consideration all the elements that make this composition work so well, the craft is well done. Congratulations.