First you open the back door to let the old year out, and then you open the front to let the new one in. The "First Foot" in the new year should belong to a tall dark handsome stranger, and he should bear a gift, usually a lump of coal tied with a ribbon. Also carried in Scotland is a dense dark fruit cake called Black Bun, and a bottle of whisky doesn't go amiss. Years ago people also used to bring a red herring, which was wrapped with the head showing over the wrapping, like a fish in a dress. I believe that some were dressed quite elaborately.
Happy Hogmanay....John