Principles are ways of successfully dealing with reality to get what you want out of life.
Ray Dalio, one of the world’s most successful investors and entrepreneurs, cites principles as his key to success.
Remember that your goal is to put the right people in the right design. First understand the responsibilities of the role and the qualities needed to fulfill them, then ascertain whether an individual has them. When you're doing this well, there should almost be an audible "click" as the person you're hiring fits into his or her role.