After the snow has fallen, and the sun comes out in the afternoon or the next day, you can have a beautiful untouched snowscape for your photographs.
If the sun is shining and there is snow on the ground, you will have a very bright scene, because the snow will reflect the light. You need to decrease your ISO to probably 100 or 200. But you do not want to blow out the detail on the snow by overexposing and you do not want gray looking snow because your light meter underexposes the scene. To get a well exposed photo in the snow you will want to increase your exposure compensation in your camera to +1 or +2. If you are using a point and shoot that does not have a control for exposure compensation, then meter for the sky using spot metering or partial metering.
If you are shooting a horse in action in the snow, make sure you use shutter priority and increase your shutter speed to at least 1/1000. You can photograph people riding in the snow, horses running in the snow, and even wild horses in the snow. Bundle up, and enjoy!