Not move from in front of the door after boarding

Your job is not done when you board the train. Too many times have I seen a person dash onto a train, flash that smug smirk of satisfaction that says, "I made it. I am on the 4 train!" and breathe a sigh of relief. A half-second later this self-absorbed rider is being pushed from behind as more people try to replicate his amazing feat. Despite oodles of real estate in the middle of the car, the dasher stays where he is, hoping for an easy exit or perhaps not aware that the floor is just as solid six feet away from the door as it is two feet away. Because of his ignorance, two or three people are left to wait for the next train as they see right through the car where the original rider should be standing.

This is no good. Until they incorporate moats, subway doors do not need gatekeepers. If you're worried about being able to get off at your stop, don't be. You will not be the only person to change trains at Grand Central. I CANNOT BELIEVE 12 PEOPLE ON ONE SUBWAY CAR ALSO COMMUTE BY METRO-NORTH. AND DURING RUSH HOUR TOO! WHAT ARE THE ODDS? If you want the door to lean on, wait until people have stopped getting on and claim your spot. That is still a dumb (and lazy) place to stand, however, as more people will try to get on at the next stop.

And if you do decide to block the door, do not compound matters by sighing in disgust as people politely say, "Excuse me" in their effort to get by you in to the relative comfort of the center of the car. Step aside, or, better, yet, go there yourself. You'll find it a lot less crowded anyway.