There a lot of reasons to carry a knife, one of which is the "3 Blade Rule". This rule is that if you carry or have available a folding knife, a fixed blade knife, and a multitool, you can solve most problems that come up.
The most common knife everyone carries is a pocket folder. I carry one every day, but I want to challenge the orthodoxy on this. Most people carry it clipped to the strong side pocket. If you aren't carrying a firearm, that's right. But, if you are carrying a defensive firearm, the pocketknife should be clipped to the WEAK SIDE pocket. Here's why, the strong side hand should only be used for the firearm defensively. If someone tries to disarm you, you can use the strong side hand to retain the firearm, while the weak side hand draws a knife and is put to work slashing the attacker's arm.
I'm a strong proponent of carrying a fixed blade on your body. You need to understand your local laws first. Michigan law, for example, says you can't carry a blade with a length longer than 3 inches concealed with UNLAWFUL intent; self-defense is lawful. Michigan also has an exception to that for "hunting knives, carried as such". Well, coyote and pig hunting are open year-round. An $11 small game license is a good investment. I was on my way to or coming from hunting.
If you are going to carry both, as I often do, I carry the folder in my strong side pocket and the fixed blade on my weak side belt.
Any time that you carry a fixed blade, it should be on your weak side, with the blade facing FORWARD. This is the standard in the US Marine Corps for carrying the bayonet or fighting knife. The reason is the same as the Samurai, who first taught it. No matter which hand I draw it with, I can slash as I draw. If I reach across my body with my strong hand, as I draw, I am slashing forward. If I draw with the weak hand, I have the knife in a reverse grip and can also slash by crossing in from of my body with the knife. This carry method gets teh knife into the fight instantaneously.
If you work in a situation or live in a state where that is not practical, I recommend putting it on the strap of your Get Home Bag. This way, I'm not carrying it concealed on my body. If I have to throw on my Get Home Bag, most concern for the law has already gone out the window, BUT it's still carried openly and not concealed. You could also mount it handle down on one of the sides of your Get Home Bag, but I don't recommend on the back of the bag, because someone can approach it without being seen.
I keep a multitool on each side of my Get Home Bag, and I keep one on my belt as well. Each of these is slightly different. I keep a Gerber standard one on my belt, and a Gerber Diesel (which accepts different screw heads) on the bag in case I need more advanced work. The other one on my bag is an SOG EOD tool, because you never know when you might need to crimp a blasting cap.....actually I use it for installing covert cameras.
Carrying a knife is also part of American Heritage and most other cultures. It's one of the first tools man created and it's for far more than just self-defense.
As a warrior-culture idea, everyone should learn how to fight and defend themselves with the knife because it breeds a fighting attitude, develops self-confidence, and builds a warrior spirit.
Personal note: I am vehemently against carrying a karambit. It requires advanced training and is only useful in a limited set of very specific circumstances. Make your own decisions, but learn to use a standard knife first. Also, it's hard to justify to an over-zealous police officer why you are carrying a karambit. With my Taurus Toureiro or a Ka-Bar, I was or am going to go hunting or camping. Simple.
Be prepared, friends.