Depends on what public transport we are using
But ill leave some general rules for you to choose from
1. Buy a ticket (bus, train, airplane etc)
2. Validate your ticket (bus)
3. Be respectful to other passengers
4. Don't interrupt the driver
5. Dont talk loudly
6. Dont block corridors
7. Give your seat up for elders and pregnant women (bus usually)
8. Don't push people when you get off the bus
9. Sit appropriately