What is the best technique for using a drywall mud sander to achieve a smooth finish on walls?

The best technique for using a drywall mud sander to achieve a smooth finish on walls is to start with a coarse grit sandpaper to remove any bumps or imperfections, then switch to a finer grit sandpaper for a smoother finish. Sand in a circular motion and be sure to feather the edges of the mud to blend it seamlessly with the wall. Vacuum or wipe down the walls after sanding to remove any dust before painting or finishing.