Healing and injuries! Most of these deal with what happens when there isn't a magical healer standing there to immediately patch you back up.
Shot in the Shoulder: Despite what you see in the movies, getting shot or stabbed in the shoulder, shoulderblade, or collarbone area is not a walk in the park, and you're probably not going to want (or be able) to move that arm if it does happen. In fact, you're probably going to be on the ground and screaming like a little girl. There's a lot of bone and muscle, as well as many tendons and ligaments, and bullets tend to fracture bone and send sharp chips through the adjacent tissue.
Chest Wounds: A puncture wound to the chest can easily kill you, even if it doesn't hit your heart. The space between the lungs and rubs (the pleural space) is airtight, and breathing depends on the vacuum created by the diaphragm. If you get a puncture wound, you'll develop what we call a sucking chest wound. Each time you breathe, air will be sucked into that wound (and it makes a really nasty sound), and it will eventually collapse your lung and displace the contents of your chest to the other side. Your trachea will shift to one side, which is the visible sign of altered pressure inside the chest cavity, and you'll feel like you can't breathe. That's because you...can't breathe. All it takes to cover a sucking chest wound, however, is a piece of airtight material placed over the wound and sealed down on 3 sides (you don't want to seal it on all sides, to allow trapped air to escape).
Fractured Femur: A fractured femur is among the most painful injuries a person can receive, and if the break is bad, it's basically a death sentence. The marrow and blood vessels in/around the bone bleed profusely, and the femoral artery also runs very near there and can be sliced open or compressed (cutting off blood supply to the leg) by a compromised bone. If the femoral artery is nicked, you'll bleed out in 3-5 minutes and there ain't nothin' you can do about it.
Mangled Hand: You have a lot of tendons and muscles in your hands. If you slice a tendon, it snaps back and retracts into the tissue on either side. Sometimes the tendon can be found 3 or more inches away from where the initial break/cut happened, and it takes a surgeon skilled in microsurgery to retrieve that tendon and repair it. Even if they do repair it, it's forever going to be weakened, and you may never regain full range of motion.
Head Wounds: If you break your skull, the biggest danger isn't the immediate trauma to surrounding brain tissue. It's actually the blood vessels and the cerebrospinal fluid that swell or build up and increase intracranial pressure. Your brain tissue is approximately the consistency of firm Jell-o, and if you squeeze Jell-o, what happens? Yep. That happens to your brain. If you manage to survive the initial injury and swelling without major physical/mental deficits, your next issue is the possibility of infection. There's something called the blood-brain barrier, and it makes it difficult for infectious agents to cross from the bloodstream to the brain. Unfortunately, it also works in reverse, so if bacteria or parasites are introduced to the brain through an injury, the antibodies and white blood cells in your blood won't be able to cross over and fight the infection very easily.
Gut Wounds: You don't die when your intestines are hanging from your body. At least not immediately, as long as the blood flow is intact. You can also survive the loss of a good amount of intestine, as long as the doc is skilled at re-attaching the ends to each other. If the stomach or intestine is punctured but not hanging outside of the body, the biggest problem is infection. Peritonitis is the infection of the lining of the abdominal cavity, and it's extremely painful and can be deadly. Appendicitis can result in this if left untreated, as the infected organ can burst and spew all that lovely bacteria everwhere.
Dental Hygiene: Believe it or not, people actually did care about dental hygiene in pre-industrial societies. Many native cultures use(d) something called a chew stick, which is the end of a stick that is frayed into tiny wood fibers (like toothbrush bristles), and they brush their teeth with that. Most use tea or alcohol as mouthwash after they've brushed.