Don't focus on the power. Focus on your passage through life.

Balance independence with consideration and empathy.

That is to say, be conscious of other people's preferences and desires but don't let yourself be dominated by others. Maintain a strong sense of yourself while still accommodating other people.

Keep that balance, so that you come across as strong and independent and in charge of your own life and kind and considerate and concerned for others, and "soft power" is just there to be had. People will just naturally seek your counsel and generally follow your lead.

That's also how you develop and exercise it as a nation-state. And that's why Trump has so completely destroyed US soft power - because he possesses and exercises none of those qualities. He, and the nation under his leadership is boorish and aggressive and inconsiderate, and also callow and thin-skinned and petty.