The Alps are notorious for surprisingly high levels of reflected UV light, especially when the ground is covered in snow. Wear cream and protect your eyes - just as if you were skiing. See photo of full kit at the top of this page. I have to start out from home on a descent, so I always have my windproof on as I leave. Eating and Drinking Before training, I always have a good breakfast including a good hot drink.
Extra energy is needed for climbing and for the cold temperatures.
To get around this problem I take a large cycle-bottle, fill it with scalding hot water, then place it in a very thick sock doubled back on itself. This insulation keeps the water warm for about three and a half hours. It would be too cold to drink after four hours. The warm water is very soothing to the throat, and helps to offset the adverse effect of constantly breathing in cold air. You can add carbo powder to your drink, but for me in winter I prefer to eat cereal bars.