In case you didn't : use one focus point only for this focal distance and because of the shallow DOF, focus on the eyes. My experience with this lens is that is almost impossible to use more than one focus point at long focal distances.
Nevertheless, it's a nice shot.
Nice composition and expression capture. Despite the IS, 1/60 might be too low a shutter speed for 255mm. ISO 400 or even 800 would give a faster shutter speed.
