Lightly sand the ceiling surface using a drywall pole sander to remove any remnants of the acoustic "popcorn" material from the ceiling. Due to the potential health hazard of the material, eye and breathing protection should be worn until the material is no longer present.
Access the ceiling from a stepladder and apply a thin coat of lightweight latex putty to each surface blemish using a wide-bladed putty knife. Build up the coating slightly to improve the coverage and fill for sanding.
Allow all of the patched blemishes to dry thoroughly. Sand each patch lightly using a sanding block or pole sander to smooth the patch.
Blend the filled area to flush with the ceiling surface. Additional coatings can be made to level and repair larger gouges, scrapes or other damaged spots, if necessary.