The key to achieving a sharp and clean design with your stencils is to apply the icing in a consistent and even manner. Start by using a small amount of icing on your spatula or palette knife and spread it over the stencil in a smooth, gentle motion. Avoid applying too much pressure or dragging the icing across the stencil, as this may cause the design to bleed and lose its sharpness. Take your time and be patient to ensure a precise outcome.