What is done to prevent the tail hook from bouncing off the carrier deck?
The tailhook assembly on a modern carrier or terrestrial fighter has a hydraulic damping assembly which forces the hook to stay extended and dampens the impact of the hook into the runway or flight deck.  Without it the hook would bounce off the deck on impact and potentially strike the tail of the aircraft.

This was a major problem during early ship trials of the F-35C airplane the first time it went out to the boat, resulting in an unacceptable 30% boarding rate due to a faulty tailhook design.  The tailhook assembly has since been redesigned and worked well during later sea trials of the jet.

This damping assembly is quite powerful and can injure or kill careless personnel should the uplock accidentally disengage, hence the DANGER TAILHOOK markings on the aft fuselage of some navy aircraft.

The system will handle most landings; on occasion a pilot slams the jet down hard enough that the hook will jump off the deck missing all of the wires.  This is called a hook skip.  It is handled just like any other bolter: Full power at touchdown and go around to enter the bolter pattern for another try.