I usually try to do nice things all the time. If someone drops something, I pick it up for them, if I'm first to the door, I hold it open (sometimes for swaths of people, mind you), and if I see some really messed up shit, I try to make them feel better.
For instance, just the other day there was this bitch in line at the cafeteria that cut in front of this freshman with her friends, well he asked her what that was about and of course she told him to chill out because "it's just a line". Well I fucking hate that shit and so did this kid but I was in no position to tell that bitch to piss right the fuck off (though I probably should have) so he just had to wait but then I decided, hey, you know what? The least I can do is give him a cookie. So I order up an extra cookie, found him sitting with his friends and told him "Hey, sorry you had to deal with that bitch." and handed him the cookie. He was rather grateful and concurred she was just fucking rude and I left. It's acts like those were its a win-win, I feel good and so does he. It's nice to know people got your back and shit, you know?
And one other time there was a kid that couldn't pay for his meal that I was right in front of so I said, don't worry about it and gave him a couple bucks. He wasn't so grateful, not that minded, the lunch lady made him say thanks anyways but hey, it was no big deal. I like making people's days a little bit better. Because that can just fix a really fucked up day really fast.