The public transport network is made of two tramway lines and a good number of bus lines. The airport and the train station connect with tram line T2 (Peretola aeroporto, Alamanni Stazione, respectively), while the Flixbus terminal connects to tram T1 (Villa Costanza). Other long distance bus companies stop close to the train station. The tramway is quite reliable and a single-trip costs 1.70 euros, no matter the distance. Tickets can be bought in vending machines installed at tramway stations or at retailers (e.g., in "tabaccheria"). Buying a paper ticket inside the tramway is not possible, but it is possible in the bus at an increased price. You can also pay directly with your bank card inside a bus or tram, but you will not get receipts (the only proof will be on your bank summary). One card = one ticket, you can not buy multiple tickets with a single card. This system is compatible with Mastercard, VISA and American Express. Paper tickets must be validated inside the bus/tram.
To reach Porta Romana we recommend taking a bus from the train station, either line 11, 36 or 37. It's best to use the official travel planner by Autolinee Toscane rather than Google maps (an application for smartphone exists).
To reach the Arcetri hill from Porta Romana you can walk (about 40 minutes) use line 38A (small bus; towards FERMI, not to be confused with 38B; walk about 5/10 minutes), or line 11 (large bus, walk about 15/20 minutes). There are additional options, so if these do not work for you get in touch with Lorenzo, Adriano and Tomás!
Taxis are available (telephone or app: 4242), but at times rare to find.