When photographing snow you have to pretty much ignore what your camera thinks the scene looks like otherwise you will get an underexposed, grey shot. Conversely, if it’s sunny there will likely be a blue cast over the photo and the snow whites will be blown out.
So, if it’s dull and snowing take your meter readings, but then notch up your exposure compensation (EV) a couple of thirds to compensate for what the camera thought the light levels were. If you want to do it properly, zoom into a bright patch of snow, dial in an EV of between +2/3 to 1 and a 1/3 and note the shutter speed and aperture the camera’s meter obtained (or get the measurements from an external light meter). Now, go to manual mode and dial those in with the EV reset to 0. This will overexpose the snow, but give you the right effect.
If it’s sunny, use a neutral white balance card (a grey card or a patch of uncovered wall that’s grey, rocks whatever and test white balance, adjust accordingly to warm the image and avoid the blue cast. You might have to nudge down the EV 1/3 or 2/3.
Useful tips on photographing in the snow here and here and here.