1. Sometimes kindness calms the most stubborn souls. I can't find a clip, but there's this part in the beginning where Scout says "hey" to an older lady she passes by who is sitting on her porch. The lady immediately lashes out at her saying she should say "Good afternoon" and "Weren't you taught good manners?" Scout ignores her and finds her father, Atticus. They walk by her again the other direction and before the lady can get a word out, Atticus says "Good afternoon" and comes up to her, complimenting her extraordinary garden and saying all sorts of niceties. With a tip of his hat, he and Scout go their merry way. All are appeased. Did the lady deserve that sort of kindness? Probably not. Did Atticus have to say anything to her? No. But it showed that Atticus was a good man, choosing peace over pride.
2. Some of the most powerful things can be said with silence. I wish the whole scene were here because it's more drawn out and much more intense. You can sense how much Atticus despises this man, yet he's so in control he does nothing to harm him. Atticus remains unmoved by a man of whose main weapon is to frighten and intimidate others, and I believe that Atticus's unflinching manner unnerves this horrid man.
3. My personal favorite: sometimes innocence can do what wisdom can't. This is when Atticus knew there would be trouble at the jail so he spent the night in front of the innocent Tom Robinson's cell in order to protect him. What bravery Atticus and his son have, but in the end, it's Scout's innocence that saves them.