Look Me In The Eyes
Have you ever been on an elevator with a stranger and found one or both of you unwilling or unable to make eye contact? Ever wonder why? Well, it kind of depends.
They say the eyes are the window to the soul. I'm not sure who "they" are, but they weren't far off. To an educated observer, a person's eyes can speak volumes about them; who they are, what they're thinking, and more. Poker players often wear dark glasses because it is often possible to tell whether someone is lying simply by watching how their eyes move when they're talking.
There is also a certain social stigma attached to eye contact. While corporate types in Western countries will tell you that eye contact gives you an air of self confidence, cultures in the East quite literally look down on this practice. Many people in various cultures across the world consider looking someone in the eyes to be an overconfident, even rude or hostile act. It's not just an Eastern thing, either. If you were to lock eyes with someone walking down the street in downtown New York City, there's a good chance they would think you were initiating a fight.
The same is true of animals, incidentally. When teaching people about how to avoid animal attacks in the wild, experts always advise that you avoid eye contact, as this is considered a hostile action by most all mammals. The only time this isn't advised is when encountering a tiger or other large cat in the wild. Tigers tend to be conservative killers, looking for the easiest prey possible to attack, usually with the element of surprise. If they see you locking eyes with them, they not only know you know they're there, but they think you mean business. Then they're most likely to turn and leave in search of an easier meal.
In the human world, eye contact is still a powerful gesture. It's the most intimate thing you can do to another person without touching them. To a close friend or family member, this may be welcomed, but a stranger is likely to subconsciously feel threatened by it. If you try to lock eyes with a random stranger, most will be intimidated and look away, or more rarely, lock their own gaze right back, as if to challenge you. A warm smile can sometimes prevent this response, but it's not a guarantee.
So, in general, eye contact is interpreted as a hostile action, or at least an aggressive one. Unless you're in a situation where confidence is expected of you (a job interview, dating, business meeting, etc), it's probably unwise to lock eyes with a stranger.