CFR timetables are posted on large overhead boards inside the stations (gară). If you're planning to travel often by train, find and buy the current timetable book called Mersul Trenurilor at CFR stations or offices. This book lists all routes, both foreign and domestic, the trains, and their schedules. There are five types of trains, in accordance with their speed: Personal (the slowest), Accelerat, Rapid, Intercity, Express and Săgeata (the Arrow).
Buying a first class ticket provides you with an assigned seat in a cabin of six. It will cost a few thousand leu more than a standard ticket. When traveling at night, book a sleeping cabin (vagon de dormit) with two bunks and a sink. It's a good idea to bring some food and water. Also note that smoking is not permitted inside the train.
In Bucharest, the first class ticket office at Gara de Nord is in a separate hall just left of the terminal entrance off Calea Griviţei. If you have trouble communicating with the ticket clerks, try asking young people for help as they are more likely to be able speak in English, and are usually eager to assist foreigners.
Domestic tickets are usually small cardboard stubs with your wagon number and seat number written on them. You can also buy single and return tickets from CFR agencies. Getting a return ticket is recommended as it saves time on the return leg of the trip. You can buy tickets a day in advance at CFR Agencies, but only two hours before departure at the train station. International tickets must be purchased in advance at a CFR office, which are closed on weekends. You can buy return tickets from an agency if you know the exact time that you will return and want to avoid wasting time purchasing another ticket in the station when returning.