"Layer, Layer, Layer!"
This particular piece of advice is directly from the mouth of my mom, because she said this easily several times each day leading up to our first trip to Lake Tahoe, as well as several times a day while in Lake Tahoe. If we weren't bundled up to where we couldn't move, we weren't layered enough.
The idea behind layering your clothing is that although the weather is cold and snowy, by midday after skiing up and down the mountain, it's a lot warmer than you might expect. A perfect example of the many articles of clothing that one must wear while skiing is illustrated in the picture below.
My cousins, my brother and I are all in age (and height) descending order. We also seem to be in varying stages of undress. This picture is hysterical to me because Ricky (the oldest and therefore the tallest) is wearing a T-shirt with his ski pants, while his younger brother Michael (next in line in age and height) is slightly more covered up in a long-sleeved top. I am next in line with a fuzzy purple fleece sweater.
The best part of the photo is Erik, who is not only desperately trying to give me "bunny ears" with gloves on, but is also looking practically frigid in his ski jacket with the hood and face cover on. So take it from the Gedigian and McNamee families: the more you layer, the more comfortable you will be all day.