Joseph S. Nye in Foreign Policy:
When Foreign Policy first published my essay “Soft Power” in 1990, who would have expected that someday the term would be used by the likes of Hu Jintao or Vladimir Putin? Yet Hu told the Chinese Communist Party in 2007 that China needed to increase its soft power, and Putin recently urged Russian diplomats to apply soft power more extensively. Neither leader, however, seems to have understood how to accomplish his goals.
Power is the ability to affect others to get the outcomes one wants, and that can be accomplished in three main ways — by coercion, payment, or attraction. If you can add the soft power of attraction to your toolkit, you can economize on carrots and sticks. For a rising power like China whose growing economic and military might frightens its neighbors into counter-balancing coalitions, a smart strategy includes soft power to make China look less frightening and the balancing coalitions less effective. For a declining power like Russia (or Britain before it), a residual soft power helps to cushion the fall.
The soft power of a country rests primarily on three resources: its culture (in places where it is attractive to others), its political values (when it lives up to them at home and abroad), and its foreign policies (when they are seen as legitimate and having moral authority). But combining these resources is not always easy.
More here.