If the snow if close, I use my Sekonic both in incident and reflective mode with snow. In reflective mode, I get close to the snow, making sure that's all I'm getting (essentially making my meter equivalent to a spot meter reading). If there is texture in the snow, I put it in zone VIII (opening up three stops from the reading), if not, I go to zone IX (opening up four stops from the reading). I compare that to the incident mode reading, just to make sure.
If the snow is far, just part of the general scenery but not dominant, I just go with the incident reading. If you will do landscape, i.e., snowy mountains from afar, I would suggest a yellow filter. You'll get better tonal separation between the sky (slightly darken) and the snow. Snowy scenes with washed-out sky don't make for very appealing photos.
With high contrast snowy scenes, you also have to make sure you use the right developer. For example, stock D-76 or Xtol risk blowing your highlights, so best to use a compensating developer.