All timetables, routes and maps are available online.
Tickets must be bought from machines at every stop before you board. The entire city, including the airport, is within Zone 10. The most common tickets are:
"Billet Tout Genève" / All Geneva (valid for one hour, regardless of how many vehicles are taken), CHF 3.00
"Carte dès 9 heures jusqu'à minuit" / All day from 9.00 am to midnight, CHF 8.00
"Carte 24 heures Tout Genève" / A full-day city pass, CHF 10.00
Some machines only accept cash (coins, not notes). To avoid looking for coins, you can buy a “tpgPay” card (CHF 20, 50 or 100) at tobacco shops, or at the TPG Office at the train station.
For travels in zone 10 (Geneva city) only, you can also buy your ticket online or with your mobile phone via the TPG application for Apple and Android, or, if you have a Swiss SIM card, by SMS (see the procedure here). The ticket must be purchased before entering the vehicule (you must have received it on your phone beforehand).
If you stay at a hotel, it will provide you with a free city pass for public transports valid for the duration of your stay. You may ask for it at the hotel's reception.