During the day, buses and trams start the service at 5:30am and run all day until Midnight in all directions. Night buses start the service at 00:30am until 5:30 am. Buses leave from Piazza dei Cinquecento and Venice Square (Piazza Venezia) every 30 minutes in all directions. You can buy tickets for 1 euro on board.
For more information about all routes, check the official Rome Public Transportation Agency, ATAC. There you’ll find all the up-to-date information on routes, tickets, underground and urban railways, public transport maps, wait times, and all information to get around Rome. On the ATAC website there is also an useful services: route planner that allows you to enter your starting point and the destination addresses and it will provide a map of the route you should take including the buses necessary to get there.