Is it really a given that "successful" means upward mobility and financial success? Not everyone can should or wants to own a kingdom. Freedom to pursue your interests is a good goal to have - the skills you practice to get you to that point may not serve you well as you'll find you're only good at gaining money.
I don't know about best but other effective and often used methods of getting things from people include:
* Instilling a deep fear in them, so they avoid crossing you or look to you as their savior.
* Manipulating their sense of worth so they need what you are offering them to merely feel OK about themselves.
* Creating the impression that you are so important and highly valued by others that getting only the smallest amount of time from you is a great blessing.
* Telling them that other people are awful and out-to-get them, so that they need to work with you to oppose those other, awful people.
I try to avoid doing this kind of thing but these are methods that have made many people much money and earned them many dollars. Empathy is great, I support empathy and try to practice it whenever I can. It's also important to understand that real empathy isn't necessarily a skill that will help you get ahead in the present work world. Often it's a "skill" that others will aim to exploit in you.
Don't confuse being a good person and being a successful person. You might be able to be both but they definitely two different, uh, "paths". I'd encourage being a good person more than being a successful but I think everyone should have their eyes open concerning our modern world.