Let the joint compound dry completely
Put on a dust mask, safety glasses, and gloves
Cover floors and nearby surfaces with plastic or drop cloths
Use a sanding pole or sanding block with fine-grit sandpaper
Start with 120- to 150-grit sandpaper
Sand lightly in circular or back-and-forth motions
Focus on smoothing seams, edges, and ridges
Avoid sanding too hard to prevent gouges
Check your work with a bright light held at an angle
Switch to 180- to 220-grit sandpaper for final smoothing
Wipe away dust with a dry microfiber cloth or vacuum
Apply more joint compound if needed, let it dry, and sand again
Clean the area thoroughly before priming and painting