Paper tickets can be bought at selected ticket agents, at train and selected busway stations or on bus and ferry services.
If you don't have a pre-purchased ticket, have your fare (and concession card if you're buying a concession ticket) ready for the driver, station attendant or ferry master.
You can only pay with cash on bus and ferry services, and the driver or ferry master may not have change for larger notes.
Some bus services are pre-paid during peak times. You will need a valid ticket or go card or SEEQ card before you board the service.