Something that has helped me a lot on a personal level is getting to know and understand myself. My wife has helped with this more than I ever did by myself, using the knowledge she acquired while getting her undergrad in psychology.
The most helpful of these tools for me has been the Myers-Briggs personality test. It is very specific and, in my case, very accurate.
I am an ENTP on the Myers-Briggs scale. Knowing this has helped me to discover and improve weaknesses as well as cultivate my strengths. Occasionally I fluctuate to an INTP, but my extroverted side is definitely dominant. Introversion is used for repair and discovery of my self.
Most psychopaths are ENTPs. When I found that out, I found out that psychopaths aren't all that bad. They're not serial killers, that's a different thing. Psychopaths are just really selfish. Selfishness is a characteristic of an ENTP.
ENTPs are not good with emotions. I'm an extreme example of this, because I intentionally seek to eliminate emotion as a significant part of my life. It slows progress and makes decisions more difficult than they have to be. That's something the wife and I clash on, because she is a very emotional person. I'm having to work on myself to help me see her point of view.
ENTPs need to be right. I've embraced this quality. Research and learning are important to me. I try to set up a system of people around me who will challenge me to see things differently, because I may be wrong about something and be unable to see it by my own power yet.
I know this isn't my first post, and I already did a self introduction post, but the tag fits this topic. I encourage everyone to look up a Myers-Briggs test and answer the questions honestly. To apply the quote from Sun Tzu, think of everything you do as a battle. Succeeding at work, starting your business, raising your children. If you know your own weaknesses and strengths, you will have an advantage in life.
We'll talk about knowing your enemy later.
Til then, let me know what your Myers Briggs classification is. I want to know!
Nate