Personal Background:
I am 65, have never been active duty military, nor in law enforcement. I have, however, legally (licensed CCW) carried a concealed handgun on a regular, daily basis, for most of my adult life. This includes CCW permits in Oregon, Washington, Alaska, and Indiana. When specific circumstances justified doing so (in my personal opinion at the time), I have also carried concealed in California "from time to time" without a CCW. I helped teach a concealed weapons class when living in Alaska by demonstrating how to carry effectively, regardless of weapon size. I have also had no fewer than seven instances in the last forty years when I have had to legitimately use a concealed handgun for personal defense of self or others. These include a home invasion attempt, an attempted "run my wife and I off the road" on a dark, deserted stretch of highway one night, two serious mugging attempts, two cases of effecting citizen's arrests at gun point for attempted thefts while working as a late night cashier at a convenience store, and (most recently), intervening in a domestic dispute gone bad where the male half attempted grave bodily harm on his (ex)fiancee by taking a shot at her in front of my house. Please note my use of "attempted" in all of the above cases. Thanks to my being legally armed at the time, none of them were successful. Equally fortunate, all were successfully resolved without my actually having to fire a shot in any of them (although three were really, really close). The above is just to support that my personal opinions below are based on many years of actual street experience as a civilian carrier of a legally carried concealed weapon.

Legal Considerations:
There was a recent post about an individual in Washington State who was pulled over for a routine traffic stop. Said individual happened to have two loaded, concealed weapons in his vehicle, one handgun and one rifle. What said individual did not have was a CCW. In addition to whatever resulted from the traffic stop itself, both weapons were confiscated and the individual ended up with a conviction for carrying a concealed weapon without a license.
I too been pulled over for routine traffic stops while carrying concealed, once in Anchorage, Alaska (failure to signal a lane change) and once in Seattle, Washington (cracked windshield). In Anchorage, I immediately informed the officer that I was licensed and carrying and asked if he wanted to secure the weapon. His reply was "No. You have done what you are required by law to do - inform me that you are carrying. It is safer for both of us if you just leave it in the holster."

The difference between Anchorage and Seattle is that the two officers in Seattle did want to secure any weapons. By the time I was done divesting myself of any questionable items, there were two J Frame S&W .38s (both with Crimson Trace laser grips), a Colt Mustang Pocketlite .380, a Benchmade lock-back folder, a Leatherman Wave, a Swiss Champ knife, a canister of Pepper Spray, and an ASP tactical baton on the hood of my car. Reaction to what the liberal media would describe as a walking arsenal? One officer turned to the other and said "S***, he's got better gear than we do."
In both cases, I drove away with nothing more than a verbal warning, one to watch my lane changes and the other to get my windshield fixed. I have always suspected that my being legally armed and cooperative was a factor in receiving verbal warnings instead of written tickets.

I am a Life Member of the NRA, as pro Second Amendment as anyone reading SurvivalBlog, and personally believe that the only two states that have "got it right" are Vermont and Alaska, both of which allow concealed carry, with no permit required [even inside city limits]. Having said that, I also recognize that the remaining 48 states DO have restrictive laws governing the carrying of concealed weapons. I also recognize that, at least for the time being and immediately foreseeable future, they also have functioning law enforcement and judicial systems. While I may agree with the sentiment that no law abiding citizen should be required to have a license to exercise rightsguaranteed under the Constitution, I also have no sympathy for anyone who assumes that position, gets caught, and ends up paying the legal price.

The question I would ask anyone who is considering carrying concealed without the necessary legal permit is this: Is the exercise of your principles worth the risk of losing the weapon(s) you are carrying, a criminal conviction that will probably result in failed background checks for any future purchases requiring Federal paperwork, and the distinct possibility in today's political environment of the stop/conviction triggering a search warrant of your home (and subsequent confiscation of any weapons found there) because DHS criteria suggests that you are obviously a dangerous extremist, if not an outright terrorist? Let your conscience be your guide. Just be sure to very carefully think through the potential ramifications of your actions.

CONVENTIONAL WISDOM:
The absolute Rule Number One of gunfights is simple and basic: Have a gun. Not only do I totally agree with Rule Number One, but without exception, all other considerations in the concealed carry decision process are insignificant compared to Rule Number One.

Rule Number Two generally involves weapon choice - revolver versus semi-auto. Depending on who is on the soap box at the moment, myriad reasons will be

Rule Number Three generally involves the best caliber. As with the revolver versus semi-automatic decision, one size does not fit all. While there is much truth to the old statement that a 9mm may expand but a .45 will never shrink, the size of the hole is of far less importance than the location of the hole. Bore diameter is nowhere near as critical as shot placement.

Rule Number Four deals with the How and Where to carry. The vast majority of gun writers/instructors teach/preach strong-side hip, preferably in an inside the waist band (IWB) holster. This is an excellent choice. But as with Rules Two and Three, one size does not fit all. There are numerous reasons why this may be a less than optimum method of carry, depending on specific circumstances at the time.

Rule Number Five is to always carry at least one reload of spare ammo in either a spare magazine for a semi-auto or some kind of speed loader for a revolver. I totally agree about carrying spare ammo. I just don't necessarily agree on the best way to do it.

Rule Number Six is to always use "aimed" fire by focusing on your front sight.

Rule Number Seven is the true weapon isn't the gun; it is the person holding it.

UNCONVENTIONAL WISDOM:
Rule Number One: See above. No disagreement here at all.
Rule Number Two: See Rule Number One. Whether it is a revolver or semi-auto, your first choice should be the biggest (in terms of both caliber and capacity) that you willalways have with you. A $2,000 tricked-out custom [Model] 1911 with all the latest bells and whistles is worthless if it is back home in your gun safe (you do have a gun safe, don't you?) when you need it on the street. Having a carry gun that you don't carry all the time because it is too big, too heavy, interferes with your clothing style, or any other lame excuse you come up with, makes no sense at all in my book. If you have made the decision to carry, then do so. Period. No exceptions. It makes not one whit of difference if that choice is a revolver or semi-auto as long as it is one you will always have on/with you. It makes a whole lot of difference if it is at home and you aren't, regardless of type.
Rule Number Three: See Rule Number One. Years ago (before the days of high performance JHP bullets) caliber choice did make a difference in terms of proven street performance. After many, many years of documented shootings, the 125 grain JHP .357 Magnum still holds the position of number one, one shot stop performance. It is followed very closely now by the .40 S&W, with the .45 ACP marginally behind the .40. Today's high performance loads for .32 and .380, however, are vastly superior to the old 148 grain lead round nose .38 Special police loads, which were notoriously poor stoppers.

The point is that the caliber itself is not the key factor. What is the most effective (note that I said effective and not largest) caliber that you can comfortably handle and reliably control? My daughter and a personal friend of ours both have a medical condition which makes it physically impossible for either of them to control any semi-auto chambering more than a .380. "Muzzle flip" with heavier loads will literally dislocate their wrists because most of the recoil force is transferred directly to the wrist joint. Both of them, however, can very easily and comfortably control full frame .45 revolvers. This is because grip angle on the revolver transfers recoil into the web of the hand between the thumb and pointer finger and then in a direct line through the wrist and down the forearm. Not only is perceived recoil considerably reduced, actual recoil force applied to the wrist joint is in fact reduced.

Re-stating Rules Two and Three: See Rule Number One. What works best for you? You need to stop caring about what works best for someone else. Concentrate instead on what works best for you and in a type/caliber configuration that you will always have with you. Front Sight's motto of "Any gun will do, if you will do" is absolutely true.
Rule Number Four: Are you ready? Can you guess? See Rule Number One. There is no question that a good IWB holster is one of the most effective ways to carry (and more importantly conceal) any handgun, especially full frame revolvers or semi-autos. Because the holster and lower portion of the weapon are inside the pants, nothing is visible below the level of the belt. Being inside the pants also allows you to cinch your belt tight, pulling the entire gun frame into your body instead of allowing it to flop outward, "printing" on your shirt or jacket. This is especially important if you are carrying a small revolver in a belt holster because they are "top heavy" with a tendency to have the butt of the gun flop or sag away from the body. But unless the IWB holster is properly designed to stay open with the weapon removed, it is virtually impossible to re-holster the gun one-handed.

But as effective as it might be, an IWB is not always your best choice. Do you spend most of your working day behind the wheel of a vehicle? Try drawing from a strong-side hip IWB holster some time while you are sitting behind the wheel, with your seat belt going over your jacket. Under these circumstances, a good shoulder or cross-draw holster would be infinitely more practical. Or maybe you work in an office that doesn't have air conditioning in the hot and humid summer months. I can guarantee you that your co-workers will find it odd or strange that you are the only one in the office who never removes your coat. Been there. Done that. Switched to a different carry method.
Rule Number Five: Again, See Rule Number One. Given the proliferation in recent years of high capacity semi-autos using double stack magazines capable of holding 15 or more rounds, there is a tendency for the neophyte (and even some with more experience who should know better) to assume that spare ammo is unnecessary. The logic runs "If I can't resolve the problem in 15, or 17 or 19 rounds, I won't need spare ammo anyway." I don't care who the manufacturer is or how high the quality of the product, if it is mechanical, it can break or malfunction. Or, as I read recently, "Anyone who tells you they have never experienced a breakage is either lying or they don't shoot enough." With proper training, you can very quickly clear typical semi-auto jams or malfunctions. But if the magazine itself fails (like having the floor plate come loose, dumping all remaining rounds on the ground), the only way to get back in action (short of picking up one round at a time from the ground and hand feeding it in the chamber), is having a spare reload.

In spite of the argument that revolvers are more "functionally reliable" than semi-autos, they are not immune to problems. Older style firing pins can break. Inadequate crimping can cause bullets to pull forward from the case, locking up the cylinder. The early-production Model 586 L Frame S&W .357 Magnum had a design flaw that would cause primers to back out of the primer pocket, which would also lock the cylinder, preventing cylinder rotation. There is no "rack and tap" clearance drill for a locked up revolver cylinder. The only remedy is disassembly, which is best left to a qualified gunsmith. I was fortunate that my 586 locked up on me while testing it at the range and not in the middle of some serious social interaction. Or I should say, the 586 that I used to own.
Where I personally differ from Conventional Wisdom is that I don't carry spare ammo for my primary strong side hip holstered weapon (either a Browning Hi-Power in .40 S&W or a Kimber Gold Match 1911 in .45 ACP). I carry a spare gun (Taurus 605 .357 Magnum with a 2-1/2 inch barrel). What I give up in the way of spare rounds (5 rounds of. .357 vs 10 .40 or 8 rounds of .45) I more than gain in speed and versatility. This is what is known as a "New York Reload" based on NYPD's famed Stake-Out Squad. Simply put, the fastest reload in the world is a second gun.

That by itself is enough reason for me to carry a spare gun instead of spare ammo for my primary. But there are other reasons that, again for me, are even more important. If you are ever faced with multiple assailants and are with someone, tossing them your spare magazine won't do either of you much good. Tossing them your spare gun might. What if you are out with your family some dark and rainy night and your car breaks down in a questionable area, requiring you to walk for help? (Yes, you should have a functioning cell phone for those situations. Is it fully charged? Do you have a charger in the car just in case it isn't? Are you in a dead zone with no phone reception?) If it is necessary for any reason for you to leave them while you seek help, do you take your gun with you (leaving them defenseless), or do you leave your gun with them (leaving you defenseless)? This becomes a non-issue with a spare gun.