First thing I did after reading the article was to CTRL+F "influence people". Truth be told I probably never needed it, but it put things I had been doing my entire life, at times without realizing, into words better than I could have and so I knew that the remaining quarter I hadn't been doing was the very truth, and I got to it while still in uni.

The biggest lessons that stuck with me, who really liked discussing to the level of debating when I was younger, were to never correct somebody to their face, and to, whenever I was in the wrong in the slightest, admit my mistakes quickly and with downright enthusiasm.
The latter is not only a great way to be honest to yourself, to maintain integrity, to never suffer that slimy feel after trying to weasel your way out of something, but admitting you were wrong about something will help you get more out of almost any argument or situation, despite what one might assume at first.

I'll quote the relevant part, and despite looking like a big block of text, it is really easy to read and remember well:

"I frequently walked in this park with Rex, my little Boston bulldog. He was a friendly, harmless little hound; and since we rarely met anyone in the park, I took Rex along without a leash or a muzzle. One day we encountered a mounted policeman in the park, a policeman itching to show his authority. "What do you mean by letting that dog run loose in the park without a muzzle and leash?" he reprimanded me. "Don't you know it's against the law?" "Yes, I know it is," I replied softy, "but I didn't think he would do any harm out here." "You didn't think! You didn't think! The law doesn't give a tinker's damn about what you think. That dog might kill a squirrel or bite a child. Now, I'm going to let you off this time; but if I catch this dog out here again without a muzzle and a leash, you'll have to tell it to the judge." I meekly promised to obey. And I did obey - for a few times. But Rex didn't like the muzzle, and neither did I; so we decided to take a chance. Everything was lovely for a while, and then we struck a snag. Rex and I raced over the brow of a hill one afternoon and there, suddenly - to my dismay - I saw the majesty of the law, astride a bay horse. Rex was out in front, heading straight for the officer. I was in for it. I knew it. So I didn't wait until the policeman started talking. I beat him to it. I said: "Officer, you've caught me red handed. I'm guilty. I have no alibis, no excuses. You warned me last week that if I brought the dog out here again without a muzzle you would fine me." "Well, now," the policeman responded in a soft tone. "I know it's a temptation to let a little dog like that have a run out here when nobody is around." "Sure it's a temptation," I replied, "but it is against the law." "Well, a little dog like that isn't going to harm anybody," the policeman remonstrated. "No, but he may kill squirrels," I said. "Well now, I think you are taking this a bit too seriously," he told me. "I'll tell you what you do. You just let him run over the hill there where I can't see him - and we'll forget all about it."
That policeman, being human, wanted a feeling of importance; so when I began to condemn myself, the only way he could nourish his self-esteem was to take the magnanimous attitude of showing mercy. But suppose I had tried to defend myself - well, did you ever argue with a policeman? But instead of breaking lances with him, I admitted that he was absolutely right and I was absolutely wrong; I admitted it quickly, openly, and with enthusiasm. The affair terminated graciously in my taking his side and his taking my side. Lord Chesterfield himself could hardly have been more gracious than this mounted policeman, who, only a week previously, had threatened to have the law on me. If we know we are going to be rebuked anyhow, isn't it far better to beat the other person to it and do it ourselves? Isn't it much easier to listen to self-criticism than to bear condemnation from alien lips? Say about yourself all the derogatory things you know the other person is thinking or wants to say or intends to say - and say them before that person has a chance to say them. The chances are a hundred to one that a generous, forgiving attitude will be taken and your mistakes will be minimized just as the mounted policeman did with me and Rex."