The S.M.A.R.T. principle provides a framework for setting effective project goals by ensuring they are Specific, Measurable, Achievable, Relevant, and Time-bound. By answering the five 'W' questions and systematically addressing project concerns, one can enhance the likelihood of success and avoid lost sales, as illustrated by a case study on managing inventory. Implementing this principle helps break down long-term objectives into manageable short-term achievements, promoting progress and satisfaction.