What can I use to get the white (snow) off my black ugg suede boots?
It's probably salt stains. You will need to wash and dry your boots then brush them.
The white (snow) can easily be removed by placing your boots in a warm place and let the snow melt away. If there is any stain, you will need a brush and minimum amount of water. You can get some tips at http://www.whooga.co.uk/Cleaning-Ugg-Boots.