When choosing a holster, your first priority will be concealability. It must be positioned for fast access, ideally with either hand. Perhaps the best holster when wearing a
suit is the crossdraw over the hipbone. It's especially good for when you're standing in a secure position, your back to a wall,
arms crossed, and hand on your
weapon.
Another type is the down-slanting shoulder holster, which is similar to the crossdraw but does not offer as much accessibility to the weak hand. A shoulder holster, however, is the best choice for a bulky handgun.
There is also something called the Jackass shoulder system. It works like a vest and has a double magazine pouch under the strong side arm. Ankle holsters are usually good only for carrying the number 3 weapon, because the access is slow. Women tend to favor the shoulder holster or vest with built-in holster.