I just did this, to photograph the ponte pants too actually. I would say take the photos in natural light, but not direct sunlight. (I find the light best in my apartment in the morning, but you might need to experiment with different spots), and do not be tempted to use the flash (I never use mine actually) - it does show more detail but makes things look oddly contrasty and shiny.
Another thing I often do is duplicate the photo and up the exposure and/or brightness/contrast A LOT (you basically want your face to be completely washed out to get decent lightness on the black). Most simple photo programs (I use iphoto for this) let you do this simple alteration. Obviously this makes the black appear grey but you can see details a lot better. I did it on photo #2 here:
http://youlookfab.com/welookfa.....onte-pants
