How can I achieve a smooth finish when sanding trim?

To achieve a smooth finish when sanding trim, start with a coarse sandpaper to remove imperfections, then switch to a finer grit sandpaper for a smoother finish. Sand in the direction of the wood grain and use a sanding block to keep the surface even. Finish by wiping the trim with a damp cloth to remove dust and debris before applying a final coat of paint or stain.