Respect Personal Space
If you think you can avoid the anxiety of commuting by driving, you can't. Traffic sucks. However, you rarely have to worry about a snoozing research analyst using your shoulder as a pillow or the "accidental" graze of a leering weirdo. To the creeps out there, don't use a packed subway car as an excuse to get close to a girl. You know how far women stay away from you on the sidewalk, or in a nightclub? That's not an accident.
"Personal space" is not limited to a physical area. It also includes violating our mental tranquility by striking up a conversation. When it comes to public transit manners, take the advice of Keith Sweat and talk to nobody. If you catch a glimpse an old friend or coworker on the platform, pretend not to see them. The guilt of aggressively avoiding people is far less taxing than shoehorning small talk into the length of your morning commute.