Is the light white or yellow? Best is to use fluorescent lights. The pictures are dark (underexposed) in general, that means that there's not enough light reaching the sensor.
If you have a camera that has Auto setting as well as aperture and shutter priority ditch the Auto and shoot in aperture priority with a tripod. Set the aperture to F4.0 minimum and let the camera compute the exposure time necessary for good pictures. Also keep the white balance in auto for now, you can play with that later.
If your camera only has auto the only solution is to get more powerful lights or shoot outside in day light.
xPLAN303Ex: The portrait of the artist I am not.