Think of parenting, teaching, sports, etc. and the value of a mentor is indisputable. Organizations and businesses that are skillful in implementing a mentoring culture perform better and have happier members and employees.
How to close a sale? A great list of under-utilized common sense. I think sometimes certain tactics are too obvious to be trusted, and we sales folk go the long way because the short road is suspiciously short. They are called fundamentals for a reason.