It looks like we're going to finally have a nice winter weekend here so I found a couple who is willing to give me a few hours of their time to get my first practice at doing couples portraits. I have an XTI with a 17-85 IS an a 430ex flash. We've got lots of snow on the ground so I wan't to make sure that I get a nice bright fresh look to the snow without washing out their faces - depending if it's sunny or cloudy, what can I do to ensure this? Not sure if this matters but I usually use an expo disc to help get the white balance. Any other tips that might help out a first timer?