"Connect with everyone, all the time.
Be genuine about it. Learn to find something you like in each person, and then speak to that thing."
That's probably because I think it's the only one I was fortunate to have understood well before I turned 20 all those years ago. I credit/blame my mother, who has been everyone's favorite person in whom to confide for as long as I can remember.
Anyway, I honestly do believe it's the key to happiness. And anytime I feel low and/or overwhelmed with life in general, I try and strike up a conversation with whoever happens to be around -- the person in front of me in line at the grocery store, my cab driver, whoever -- and I soon remember what we're all here for.