In addition to the above, you could definitely improve things by moving your lights around a little. Using #6 as an example, you've got almost no catchlight in her eyes, but you do have two hot spots on her forehead. This tells me that the lights were likely too far away, too high, and too much to the side. Start with a basic simple lighting plan. One light, 30 degrees off-axis set so that the centre of the modifier is even with the top of the subject's head and aimed down slightly, and a fill on-axis and one stop below key.