This is a petty observation but I've just got to flame about it.
The world is divided into two types of people; the people who say "hi" first and the people who don't.
I've spent my life always saying hi to someone the minute I recognize them. I can't help it.
Today I bumped into a dad at my son's baseball game. I don't know him well but he seems like a nice person. Every time we cross pathes I ALWAYS say hello first and then he immediately responds. I can tell he's just waiting for me to acknowledge him. Because this behavior confuses me, I try to keep our exchanges pleasant and brief.
Being a "hi" first person isn't always as easy at it looks. Maybe it's wiser to be more reserved - then you're not vulnerable. Unfortunately, that's not a world I can live in. It would make me too depressed to start screening people at this point in my life.
So I guess I'll just keep saying it.