Start with smooth, cool, room-temperature buttercream. If you’re working with a particularly fragile cake, chill the cake layers first, wrapped in cling film (plastic wrap), to make them a bit more sturdy. If you’re not putting the cake directly on to a cake plate or stand, using a thin cake board makes it easier to move the filled and covered cake around. Attach the first layer, bottom side down, to the board, plate or stand with a small amount of buttercream.