John, start with the fact I am lazy so I look for the easiest solution. Here are two pictures of one of my Christmas layouts. I just put 1/2” insulation foam over the plywood and arrange the buildings within the track plan. I use one of the cars to make slight grooves in the foam and use a mascara brush to highlight the tire tracks on the roads. Can do a 5’x8’ layout in just hours.
More detail can be added by using white caulking to make snow banks. One could paint the foam with white glitter paint first if desired. I am not a fan of loose bits of snow or glitter on a layout.
