Twist the icing bag and grip between your thumb and index finger. Place the other hand at the bottom of the bag and use this to guide the tip. Starting in the middle of the cake let the icing fall onto the cake. Then pipe over this icing in a spiral action, over piping what you already piped by about a millimetre or two. When you reach the end of your swirl and you have covered the cake release and gently pull. Sometimes the join is quite neat, however if it isn’t you can use a sugar flower or leaf to cover it.