Late night etiquette
Dorm rooms are for sleeping so if it's after 10pm and people want to sleep, let them. Don't sit there on your phone lighting up the dark room with your ominous blue screen light or have a hush-hush whisper conversation with someone - head out to the common room instead.
If you're coming back to the hostel late at night then expect to wander around the dorm quietly and in the dark. There is nothing more annoying than when you're sound asleep and someone loudly stumbles in drunk at 3am, flicks on the light switch and wakes everyone up.