The Chet of Adam HaRishon was the first sin of the universe; notice how everyone is always listening to someone else's advice, and then blaming that person. Chava listens to the snake, and Adam listens to Chava.
Dovid HaMelech was given his 70 years of life from Adam. Notice how he never listens to advice, even from Gedolei Yisrael such as Yoav and Avishai, when he suspects the Yetzer Hara is involved in that advice. We see how Dovid spent his life making a Tikkun for the weakness of Adam. Dovid specialized in going against his desires.
His Zeide, Yehuda was the same way. Even when Yitzchok, Yaakov, and all the Shevotim wanted Yehuda to burn Tamar, he went against them and admitted: צָדְקָה מִמֶּנִי she is justified.
This is the essence of true Malchus: an independent person whose main goal in life is to kill his "own" Yetzer Hara, and doesn't get persuaded by others. Shaul listened to advice [of people who were Gedolim], and got into loads of trouble. This led him to wipe out Nov the city of Cohanim, to believe that Dovid hated him, and not to wipe out Amalek completely; as a result he lost his Malchus. We need to emulate Dovid, and be at war with our Yetzer and Retzonos as much as possible.
Every person needs a Rebbe or close friend, for the purpose of helping him not do certain things he wants to do, but shouldn't. Someone called me from Eretz Yisroel with a complaint against his father-in-law. Why? He sends him various books, on topics such as personal hygiene, or about controlling your Ka'as, as if to suggest that he needs to improve in these areas. This is causing him much pain, and arousing feelings of hatred towards his father-in-law.
I told him: He obviously doesn't understand R' Avigdor Miller's rule for father-in-law's [Shut your mouth, and open your purse]. But tell me his history, and maybe we can figure this out. Sure enough, his father-in-law was a Yasom orphan at the age of six, and was never taught any lessons of life. No wonder he feels like a nobody.
I told him: Picture your father-in-law as a six-year-old nebach crying at his father's Levaya. Start making him feel good, and humor him; you'll grow in Anava. He called me back, to report that he feels like a totally different person!
Another person called from Eretz Yisroel to complain about his stubborn brother, who doesn't listen to a thing anyone says. Everyone in his family hates him, his kids can't stand him; he's impossible to live with. So I asked: How did he do as a child? He said: He was very low. He failed in everything, and was a social outcast. How about his siblings? No, they were all stars. I said: Can you judge such a person? Would you want to be in his shoes? Anyone else would just drown! If you want to judge him, look where he was coming from.
Here is a Mashal from everyday driving, to help us better understand people:
There was once a person who was driving, and in front of him was a white van. He was in a quite a rush, but the van in front was taking his time, driving like "Shabbos Noch'n Cholent". He started becoming very angry. So his passenger said: My dear friend, why are you so angry? The van has a big truck in front of him!
Before judging others, realize: there is "a big truck in front of him". This calms you down in all your relationships. Think to yourself: They are just a test from Shamayim.