Every city has its own transit etiquette, but the logic is the same: buy a pass that covers the day rather than single rides, keep the ticket until you leave the station, and stand clear of the doors. Locals look bored because they have done it a thousand times; you will look the same by the end of your first day.
Peak hours run from eight to nine in the morning and five to seven in the evening. Between them, the trains run emptier and the stations feel manageable again. If your plans are flexible, a coffee at nine-thirty beats standing in the crush at nine.
Two rules from frequent riders: keep the map on your phone before you go underground, and sit in the car nearest the exit you need. The first saves you from wandering; the second saves you minutes every day. Transit is not a compromise — it is the fastest way to see a city at street level.