All you need is a single rubber band. Criss-cross the rubber band around the hammer head so it looks like the picture above. Now, when you go to remove a nail with the claw, the metal head won't scuff up your wall.
For mysterious, quantum-mechanical reasons, the screws that hold handles and doorknobs always eventually work loose. A few drops of thread-locking compound will permanently fix the problem, yet still allow you to remove the screw with ordinary tools if you need to later. A heavier-duty variety is also available for large bolts and machinery.