Most of you have probably already seen mirror shots such as the example below. They are quite easy to do. One only needs to set the camera on a tripod and take two images of the model. For realism, the model must remember exactly where she was sitting, as well as her pose, when the second image is exposed. This was not at all difficult for the fabulous Laurel Hervert, who has immense experience in modelling:
Once processed, one only needs to stack the two images in Photoshop, then mask out part of the top layer to reveal part of the bottom image. Quite easy and fun!