The original plan was to do an outdoor portrait session. Alas, we were rained out too many times. They invited me to their house for a photo shoot, and presented me with three different lighting situations: the living room, the study and the guest bedroom. The former two (below) provided the least light, and the room decors were of a dark palette. All photos were taken by my trusty 50mm f/1.4 lens. A tripod might have helped, as I deleted some photos due to camera shake (ie, me not holding the camera steady for the duration of the shutter - the shutter is open for a relatively long time in dim light).
I was brought to the guest room third - saved the best for last! East and South facing windows, covered in gauzy white fabric instead of with wooden shutters. Made a world of a difference for natural lighting... not to mention the light pink walls to reflect some warmth onto my subject. An interesting informal comparison study on the effect of room interiors/layout on natural indoor lighting.