Decorating I found difficult, at least was my claim that the train should be recognizable as train immediately. Just leave it = shapeless pieces of cake ...
My tip: with chocolate icing (yet beautiful white chocolate) Brush, sprinkle around with solid-colored sprinkles, Wagons different color each series, as Wheels "mini Oreo cookies" (from the supermarket), or at least "Smarties" glue. Other ornamentation possible eg cargoes of sugar pearls. Our trains are on an oblong tray, for a child's birthday I glued green paper on a board and rails glued (also made of paper). But that's really a lot of work.
Points deduction is available for the types of cars. This might be more "by train" look. Remember me primarily at Castor transports.
