There are many ways to do Silhouettes, but by experimenting you can make some unique images. Rather than the traditionally way of backlighting an image, The image was first created by an overhead strobe. A red filter was placed over a reflector and the strobe was powered to about 1/2 power. The tricky part was getting the strobe the right height above the model, which in this case was about 2 feet above her head. The reflector on the strobe head has to be reasonably sealed with the filter completely around it to limit 'white light' from leaking.
The actual camera settings will vary of course, but in starting points may include the synch speed of the strobe (1/200 sec) for the shutter speed, A reasonably sharp aperture (f8) along with an ISO of 100.
These shots can be fun and creative to work with and expand images from routine to pretty amazing.