Get one that is made of "double layer" leather, . . . in other words get a lined one. Just make sure that the lining is not suede or similar type leather, . . . some suede leathers are tanned using a process that will work on the finish of a handgun, . . . especially a blued one.
Look for one that has a channel in the front of it for your front sight, . . . the holster can be sewn, laced, or riveted together, . . . those are all good, . . . but you want to see slick side leather where the leather touches the gun.
Some of the better makers also make some of their IWB holsters in a "rough side out" configuration, . . . which again puts the slick side of the leather against the weapon.
May God bless,
Dwight
