Step number one is to start thinking about dressing around the gun. Loose-fitting clothing is better than closely tailored garments. Cover garments with some "body" to them (woven cotton, poplin, canvas, leather, etc) are better than soft clinging fabrics. Cover garment must be long enough to cover the holstered handgun during all normal activities (bending over, climbing into or out of a vehicle, etc).
Next step is to consider holster designs that tend to obscure or camouflage the handgun's shape and allow the cover garment to move over the holstered handgun without snagging or "printing". Pancake-style holsters provide this benefit better than other designs.
Don't underestimate the value of a good sturdy belt that will keep your holstered handgun firmly anchored in the intended carry position. Cheaply made flimsy belts are more likely to be the problem with the larger and heavier handguns than any holster selection. Belts that are not matched to the holster's attachment points allow the holstered handgun to slide around and shift during regular activities.
I carry a full-size 1911 pistol daily using my Enhanced Pancake Model holster, usually with nothing more than a loose-fitting shirt for cover.
Occasionally I will carry a large-frame revolver (S&W N-frame or Colt SAA). These beasts have a cylinder about 1.75" in diameter and about 1.75" in length. This requires a holster that will minimize the profile of the holstered revolver. Pancake-style holsters do this better than any others. The pancake's smooth outer shell allows the cover garment to move over the holstered handgun during our regular bodily motions.
Regardless of holster style selected, the holster design must take into consideration the overall size, weight, and weight distribution of the intended handgun (including ammunition load). The balance point of the loaded pistol cannot be carried any higher than the upper belt-line without gravity taking over and tipping the holstered handgun out away from the body, compromising both concealment and security.
Thus ends this lecture on "holster design 101".
Best regards.