"Soft power" is basically your ability to get others to do what you want because there are benefits to your friendship and they don't want to lose those benefits.

So the way to get soft power is to make sure there are benefits to your friendship others don't want to lose, and then create a credible threat of losing them. Some obvious sources of personal soft power are being hot or rich, or throwing really good parties.

For example, suppose you want to get good at throwing parties. So you go out, meet some people, send out some invites, and people show up. Your place looks super cool, you put on some good music, and you spend the night making sure everyone feels welcome and introducing people and fostering conversations between them. Everyone leaves having a fantastic time. The next week, you meet some more people and invite them to your party again, and the people you invited last week invite some of their friends. Repeat for several weeks, and your parties have gone from a dozen people hanging out to 100 people packed into your house having a blast! And inevitably, someone will show up who will bring a bad vibe, and that person won't be invited back. And eventually the party simply has too many people, so you have to choose who to invite and not invite back, while still allowing new people to show up. You now have soft power. Individuals will want you to like them because they want to get invited to your excellent, exclusive parties, and want to keep getting invited back.