Don't try this at home, this is serious when it most probably relates to death. But it's important information for a writer with characters that don't have weapons handy.
1. TEMPLE – A very susceptibile vital spot. If struck with sufficient force, may cause unconsciousness or death.
2. NASION – This is the summit of the nose. If struck with sufficient force may cause death.
3. PHILTRUM – This is the area between the upper lip and the bottom of the nose. Attack to this area may also cause unconsciousness or death.
4. HOOK TO JAW – A powerful hook punch to the front side of jaw may snap an enemy's neck. Fatal.
5. ADAM'S APPLE – A sharp blow here may cause enemy to asphyxiate.
6. SMALL OF BACK – A very strong blow to the small of the back can cause the backbone to break.
7. TESTICLES – The strong, focused pain of a vicious low blow may cause shock, resulting in death.
8. BASE OF CEREBELLUM – A powerful blow to the nape of the neck, causing mortal damage.
9. COCCYX – A powerful blow to the tail bone. Fatal.
10. FULL NELSON – Stand behind the enemy, put your arms under his, and lock your hands behind his head. Bending the neck forward may either break neck, asphyxiate enemy, or cut of supply of spinal fluid to brain, causing brain damage or death.
11. HALF NELSON – Again, standing behind enemy, but one arm is used to pin one of enemy's arms.
12. BRAIN BUSTER – Bend enemy over towards you, placing him in a headlock. Grab the back of his belt, and haul him into the air, vertical, upside-down. Allow yourself to fall backward, landing on your enemy's head, which will absorb your combined weight. Most effective on concrete or gravel.
13. RUSSIAN OMELET – Cross enemy's legs. Fold enemy by pinning his shoulders to ground upside-down and placing his legs above him. Sit on his legs, folding the bass of the spine. Fatal.
14. HEART PUNCH – A strongman's attack, it is simply a powerful blow to the heart. (Many years ago, the wrestler Ox killed an opposing wrestler with this attack.)
15. UPPERCUT – An upward strike to the bottom of the jaw with the heel of the hand, causing the enemy's head to snap backward. May shatter vertabrae. Fatal.
16. ABDOMEN – A substantial blow to this area may rupture a vital organ, causing death.
17. RIB CAGE – A vicious shattering of the rib cage may cause grave internal bleeding.
18. HEAD-TO-WALL PUNCH – A swift, hard, cold-cock punch to an enemy's face while he is standing near a wall may drive his head into it, causing the back of the skull to shatter fatally.
19. PINNED DROP KICK – Standing behind enemy, holding his arms straight back. A drop kick to the back without releasing arms may severe spine, causing death.
20. HEAD WRENCH – Grabbing an enemy's head by the mouth and the back of the skull, then twisting with a sudden, violent jerk to rend vertabrae, may easily cause death.
21. CHOKE HOLD – Once a favorite of law enforcement officials, has often proved deadly. The right arm goes over the enemy's right shoulder, and grips the back of the head. The left arm comes over his left shoulder, reaches across neck, and grabs own right forearm. With enough pressure applied, causes brain damage or death.
22. HEAD YANK – Bend enemy forward, grab head, and pull back with convincing force. May seperate delicate vertebrae, causing death.
23. EARS – Coming up from behind an enemy and cupping the hands in a clapping motion over the victims ears can kill him immediately. The vibrations caused from the clapping motion will burst his eardrums, and cause internal bleeding in the brain.
24. KIDNEYS – A large nerve that branches off to the spinal cord comes very close to the skin at the kidneys. A direct blow with the knife edge of your hand can cause death.
25. EYES – Use your fingers in a V-shape and attack in gouging motion.
ALSO
Attacking is a primary factor. A fight was never won by defensive action. Attack with all of your strength. At any point or any situation, some vulnerable point on your enemies body will be open for attack. Do this while screaming as screaming has two purposes:
1. To frighten and confuse your enemy, and
2. To allow you to take a deep breath which, in turn, will put more oxygen in your blood stream. Your balance and balance of your enemy are two important factors; since, if you succeed in making your enemy lose his balance, the chances are nine to one that you can kill him in your next move. The best over-all stance is where your feet are spread about shoulders width apart, with your right foot about a foot ahead of the left. Both arms should be bent at the elbows parallel to each other. Stand on the balls of your feet and bend your waist slightly. Similar to a boxer's crouch. Employing a sudden movement or a scream or yell can throw your enemy off-balance.
There are many more ways to kill and injure an enemy, but these should work best for the average person. This is meant only as information and I would not recommend that you use this for a simple High School Brawl. Use these methods only, in your opinion, if your life is in danger. Any one of these methods could very easily kill or cause permanent damage to someone.
Found on http://listverse.com/2007/11/11/25-methods-for-killing-with-your-bare-hands/