What are the best techniques for using a drywall smoother to achieve a flawless finish on walls and ceilings?

To achieve a flawless finish on walls and ceilings using a drywall smoother, the best techniques include applying even pressure, using long, smooth strokes, feathering the edges, and sanding between coats for a smooth surface. Additionally, ensuring the drywall is properly prepared and using high-quality materials can help achieve a professional finish.