Take all decorative items off the wood stairs and out of the work area. To keep the sanding dust contained within the area where you are sanding the hardwood stairs, use drop cloths to protect the surrounding flooring from the dust.
Wear gloves, eye goggles and a protective filter mask to inhibit the sanding dust from entering your eyes and lungs. Open all windows located within the workspace to help dissipate sanding dust.
Remove dirt and small particles from the hardwood stairs by pushing a microfiber duster over the entire wood surface. Dirt or small particles that are trapped underneath the sanding pad may scratch and damage the wood of the stairs.
Examine the stairs for holes and/or nail heads sticking above the wood surface. These protruding nail heads may tear and damage the sanding pad if not repaired. Use a hammer to sink all of the nail heads that are sticking up from the hardwood surface, to below the surface of the wood. Fill holes within the hardwood with matching wood filler.
Attach a coarse-grit sanding pad to the hand-held sander according to the sander instructions. Starting on the flat surface of the treads, use the hand-held to sand the entire wood surface, working with the wood grain. Next, use the coarse sander on the nose of the stair treads and risers.
Vacuum the sanding dust with a shop vacuum. Examine the hardwood stairs for any small spots you may have missed, and sand them with the hand-held sander.
Switch to a medium-grit sanding pad. Sand the hardwood stairs with the medium-grit pad attached to the hand-held sander, starting on the flat surface of the treads, and then moving to the tread nose and risers. Continue to sand the wood surface with the wood grain until you have removed all scratches and the surface smoothness is even.
Vacuum the hardwood floor with the shop vacuum to remove all of the sanding dust.
Attach a fine-grit sanding pad to the hand-held sander. Sand the entire hardwood stairway until your surface is smooth and free from all blemishes.
Vacuum the wood surface with the shop vacuum to remove all sanding dust from the stairs.