Sometimes this is due to the way joints are bent. When posing body parts, I try to bend them in a way that is natural -- like the way my joints bend. For example, I never move the forearm side-to-side, I always twist the shoulder. I never use twist or side-to-side on the second and third joints of the fingers. You can twist the head or twist the neck. Sometimes depending on the character, it's best to do a little of both.