1) Be who you are, not who others think you should be
Unlike say, Tony Stark, when we first meet Steve Rogers, he's really not on the high end of the spectrum in many ways. Sure, he's got good old-fashioned morals, but he's still a scrawny, unhealthy orphan from Brooklyn. Yet Doctor Abraham Erskine sees something in him that makes him fit to become the ultimate symbol of "truth, justice, and the American Way". Despite the doubts of Colonel Phillips, Senator Brandt, and even Steve himself, Erskine's prediction proves correct. Steve is not "a perfect soldier", but he is still "a good man" in a time when "good men" are in short supply. He's willing to sacrifice for the benefit of the team, and he knows that true heroism is about what's inside, not the flashy outward appearance.
"Whatever happens tomorrow, you must promise me one thing. That you will stay who you are. Not a perfect soldier, but a good man."
2) Choose your friends wisely (and hope they don't come back to haunt you as a freaky cyborg assassin)
Back in The First Avenger, Cap forms his own squad rather than trusting the army to do it for him. He chooses these men because of their unwavering loyalty rather than because they're "the best and brightest". Steve chose to befriend Bucky at a young age, and their relationship has only grown since then. Even when Bucky became a rampaging mind-wiped Soviet hitman, the catchphrase of their youth snapped him back to reality.
"I'm with you to the end of the line."
3) Change is not always bad
While certain aspects of modern technology are good, some advancements come with a price. Cap comes into severe friction with Tony Stark, mostly because his showboating mode of operation ends up causing more problems than it's worth. He stands up to Stark, stating, "Big man in a suit of armor. Take that away and what are you?" When Stark responds with a snarky one-liner, Steve lectures, "I know guys with none of that worth ten of you. I've seen the footage. The only thing you really fight for is yourself. You're not the guy to make the sacrifice play, to lay down on a wire and let the other guy crawl over you." Stark again responds arrogantly, whereupon Steve coldly answers, "Always a way out... You know, you may not be a threat, but you better stop pretending to be a hero." But one of Steve's biggest worries is that a world that's changed so much no longer has a place for someone as old-fashioned as Captain America. Fortunately, Agent Coulson is there to set that matter straight.
"With everything that's happening, the things that are about to come to light, people might just need a little old-fashioned."
4) Stand up for what you believe, even if you stand alone
We all know that superheroes strive to be "better" than us normal people, and we all know they're basically the glorified police and fire department, cleaning up everyone's messes and living only to "protect and serve". Cap's point of view may not be the right one in this Civil War, but that doesn't stop him from standing up for what he believes. Cap has shown, even in the trailers, that what matters the most to him is saving lives. And Cap recognizes that, in the words of Spock, "The needs of the many outweigh the needs of the few." While Tony Stark doesn't seem to entirely grasp this concept, Cap has been standing up to bullies ever since World War II.
"I don't want to kill anyone. I don't like bullies; I don't care where they're from."
5) True heroism comes from the inside, not the outside
Captain America's entire origin story revolves around this theme. The world took a poor, sickly kid from Brooklyn and turned him into the world's greatest soldier. But it wasn't because of any great thing Steve had. When he was chosen, he was, according to Colonel Phillips, "a 90-pound asthmatic", but because of his courage and sacrifice, he became what President Matthew Ellis described as, "A symbol to the nation. A hero to the world." Because, as the Captain's Smithsonian exhibit so proudly proclaimed, "The story of Captain America is one of honor, bravery, and sacrifice."
"The serum amplifies everything that is inside, so good becomes great; bad becomes worse. This is why you were chosen. Because the strong man who has known power all his life, may lose respect for that power, but a weak man knows the value of strength, and knows... compassion."