I find it is best to take your base exposure and adjust your final exposure off that. If you are using your camera in manual, just open two f/ stops or decrease the shutter speed two f/stops. If you are using your camera in automatic, then add +2 EV exposure bias. Be careful when you do this to set it back to 0 EV afterwards, it is easy to forget and you may wind up overexposing frames you did not want to. Some of it will depend how much snow is in your image. If the snow predominates you should probably add 2 stops. If it makes up half of the frame, I would go with 1 stop and bracket.
Situations like snow is where having a 1° spotmeter really comes in handy. Sunlit snow should be around Zone VII or VIII (Using Ansel Adams' Zone System). Once you have set your exposure to place the snow in that zone, meter the other areas and see where they fall. You may have to adjust your exposure a little bit or do like I do, adjust your development time to achieve the desired effect.
