The first element to avoiding your blade is keeping it in your hand. As Fleisher's Aaron Lenz describes it, you should hold your knife like the butt of a pistol, fingers wrapped tightly around the grip "like someone was trying to take it away from you." Some people hold a boning knife like a conductor's baton during a particularly slow part of Pachelbel's Canon. This is wrong. You will either drop your knife through your fingers, causing you to cut your knife hand with your knife, or, more likely, lose track of it in your brain's motor control center and cut the hand holding the meat.
Second, do not, under any circumstances, cut toward yourself. I mean your torso, mostly, but also any other part of you. Cut away from yourself or from left to right, never towards your abdomen. Putting all your strength into a brazen "take it to the board" type of cut is a sure way to bury a knife in your chest, belly, femoral artery or ... genitals. We're not talking stitches here, we're talking surgery at best and coffin at worst. Avoid.
Third, keep everything clean. We take care to avoid fat buildup on our knife handles to prevent what I like to call "the knife handshake," which consists of having your lubricated fist slip over the grip and onto the length of the blade. Wash your hands. Wash your knives. Thoroughly. Often.
Fourth—this might come as a surprise—do not leave knives on the table, ever. This applies mainly in a butcher shop. The reason we wear somewhat garish knife scabbards on our hips is to avoid ever setting a knife on the table. Why? Our pieces of meat are large and heavy, and knives can be well hidden. Add force and weight, and you can imagine what might happen to your hand or forearm. Gross.
Fifth, bones can be really sharp. Great, it's hard enough to keep from cutting yourself with a knife, now bones? Yes. Bones, particularly the chine and feather bones along the spinal column, become extremely sharp and dangerous when cut by a carcass splitter. Add the weight of the loin, the force needed to grip and move heavy pieces of meat and the tendency to heft these pieces onto your shoulder, and you have a great recipe for slicing open a hand, arm, or (yikes!) face. The best part is that bone cuts heal fast and well.
Just in case:
No matter how much care you take, if you spend lots of time cutting meat you will cut yourself severely at some time or another. Often you will do so just when your first aid kit has hit bottom. No matter! If you have paper towels and plastic wrap handy, you have all the necessary first aid to get you to a hospital, or, less desirable, to the end of your shift. Simply wash the cut to remove any parts that don't belong to you and then wrap quickly with paper towels and plastic wrap, tightly if the cut is bad and you're on the way to the hospital, and less snug to make it through your shift without your injured extremity falling asleep.
It's my sincere hope that some of you out there will be able to avoid spilling your own blood at the expense of my own. Stay awake. Stay aware. Keep the plastic wrap handy.