I would talk to your designer and do some samples and see what they’re after. Your question is quite broad, and any suggestions we make wouldn’t necessarily coincide with your designer’s vision.
Maybe lay in some general shadow colour areas, and then spatter to your heart’s content. To create hills/mounds, you may want to look at using something like terylene to create the mounds (pull it apart and use the fuzzier side out), then sprinkle some of the plastic stage snow on it, possible a few bits of glitter, to catch the light.
Going forward, be more specific with your questions or provide an image so that we can give better solutions to your query.