Hard power is the use of carrots and sticks to bend others into following your will. Soft power is the ability to get what you want by attracting and persuading others to adopt your goals.
Both are valid tools but attraction is preferred because, with it, you don't have to buy anyone off or spend time forcing them to do what you want.
Remember, if some people are dead set against you (foes), there are others (neutrals) who often hold confused and inconsistent views of what you've got in mind. Your job is to make clear where your goals and their values coincide.
Attraction depends on credibility. That's why you must always proceed in a reasonable and even-handed manner. Arousing suspicions about the honesty and fairness of what you say will erode your soft power.
via Joe Nye