Do not stand around chatting to your friends while blocking the entire width of an access tunnel. Many commuters are desperate to get home and they wont mind if its over your crushed and bleeding body.
For the love of god when going up the escalator do not stand on the left. You walk up on the left and you stand on the right – it’s that simple.
If you are carrying a large rucksack try to make sure your hands are clearly visible at all times or you will find that your fellow passengers will slowly drift away towards the other end of the carriage. Do not leave your rucksack, or any other bag, unattended in the station or the carriage as having your luggage destroyed in a controlled explosion often offends.