Glaze your cake with a jam glaze before icing to add moisture and produce a smooth result. Allow to cool, then stand on a wire rack over a tray to catch drips of icing.
Ladle the warm icing on to the centre of the cake, forming an even puddle in the middle. Pour on more than is necessary to coat the cake. Work quickly and with a steady hand for good results.
Use a warm palette knife to smooth out the icing. Use the minimum of strokes, allowing excess to flow off the cake on to the parchment.
Without disturbing the cake, tap the rack gently to ensure the icing is even and free of air bubbles. Leave to set for 5-10 minutes.