While shooting for my cyanotypes on mirrors I shoot for the blues and whites of the resulting image. I want my images to fade into the mirrors, exposing only specific details like the subjects face. Thus I use specific lighting patterns, like the ones below.
For these I used only one light, a strobe, on the viewer's right. A reflecter could and perhaps should have been used to make the images more formally appropriate but for the cyanotypes they turned out great. Also the highlights on the nose are a bit "hot" for using the digital version of this image. Again however, cyanotypes make highlights and lowlights lose detail so it's best if the images have a lot of contrast.