When it comes to concealed carry attire, the inner waistband (IWB) holster is the most popular choice. This type of holster is designed to be attached to a belt with a loop or clip and holds a gun or similarly sized firearm inside the waist for optimal concealment. Leather is an excellent material for concealed wear as it is flexible and, with wear and tear, conforms to both the body and the weapon. A good leather holster won't add much bulk, which helps to keep it hidden.
Hidden carry holsters not only need to hold the gun securely, but they also need to help it go unnoticed. Shoulder holsters are suitable for both open and concealed carry. I have a good collection of IWB, OWB, and shoulder holsters that are great for hidden carrying. When looking for a holster that fits all your needs, consider the type of gun you will be carrying.
I usually carry a Springfield Hellcat OSP 9mm or a Ruger American Competition 9mm. If you're a woman looking for advice on how to carry concealed, check out our Ultimate Guide to Concealed Carry for Women. My personal favorite in terms of concealment and access to my weapon is the IWB: abdominal transport for my Sig 238 (only with iron sights). I initially bought a Bravo concealer, but now I use a lightweight Vedder holster that is much more concealable and comfortable.
Another advantage of shoulder holsters is that they are the only truly effective way to carry a large concealed revolver. A jacket can help hide a holster worn outside the waist. I prefer OWB holsters over IWB, even though I live in an open carry state. I always carry my gun concealed as it is for self-defense, not to prove anything or provoke unnecessarily. If you have a smaller frame, you can get away with carrying a larger gun as long as you have some volume to hide against.
A 1911 will never be well-hidden without it. After spending hundreds of dollars on holsters, I don't use one to carry my gun around my waist.