Know when the train is coming. There are lights along the floor that will flash when a train is approaching.
Stand away from the textured portion of the floor. You don't want to be too close to the train when it arrives. Oftentimes, a giant gush of air comes with the passing of the trains.
Wait your turn. On the Metro, passengers will get off the trains before other travelers get on. It's best to stand near the side of the door and enter once others have gotten off.
Step over the gap and onto the train. There is a space between the train and the platform. If you're not careful, you could get your foot lodged in the gap, or even trip. Make sure you look for this gap when you get onto and off of the Metro train.
Listen for the beeps. It sounds like two electronic chimes, followed by a recording. This is a warning to let you know the doors are about to close. You want to stand away from the doors when this happens. When the doors shut, they shut. It's not like elevator doors that will open if you stick your arm in middle. You could get hurt if you are too close.
Hold on. When the train starts and stops, you could very easily lose your balance. Many people will get up before the train stops to get close to the door. If you do this, make sure you can hold onto one of the handrails.
Line up near the door. Once the Metro train has stopped, make your way to the door. You will be expected to leave the train before others may enter. If you are not ready to get off when the doors open, others may start to get on the train, and you could miss your stop.