When deciding on the best place to conceal a firearm on your person, you must consider both the effectiveness of the concealment and the ease of access of the weapon. A pistol placed in your back pocket may be easily accessible, but everyone can see it. Conversely, a pistol strapped to your ankle under your pants leg may be well hidden from view, but will also be very difficult to reach in a hurry.
Women have the advantage in concealing weapons, as they routinely carry purses and handbags; fanny-packs can tend to stick out when men wear them. Still, if you want a sure-fire method of keeping your handgun out of sight yet still close at hand, bags and fanny-packs are hard to beat. Small handguns -- and even full-sized handguns, depending on the size of the bag -- can be hidden inside special compartments or side pouches in a handbag or fannypack without drawing much attention at all. Moreover, because they are so close to your hand, they can be easily drawn when needed.
A staple of 1950s crime drama, the shoulder holster offers effective concealment, though obviously it must be worn with a jacket of some kind in order to function properly. Shoulder holsters are not especially easy to draw from -- though they do offer a faster draw than any other method when seated -- and can be spotted by a trained eye or if your coat flutters open at the wrong moment. However, they are relatively inexpensive and can be useful for driving through dangerous areas. On the downside, they can become uncomfortable when worn for long periods of time.
Ankle holsters offer excellent concealment, especially when wearing loose pants and if the pistol is relatively small. Wearing cowboy boots with a small pistol in an ankle holster can also enhance the concealment factor. The main drawback to an ankle holster is that it is difficult to get to, especially if you need your weapon in a hurry. It can also become uncomfortable if worn for long periods of time, or if you place a heavy gun in the holster.
Smart Carry Belts (Thunderbelts)
Smart Carry belts -- previously known as "Thunderbelts" -- are holsters worn inside the pants. Most holsters are positioned just above the groin; they are designed to hold smaller, easily hidden pistols and to be worn with looser clothing. Smart Carry belts offer excellent concealment and relatively quick draw speeds, which may be offset by the fact that you now have a loaded gun pointed at a sensitive portion of your anatomy.