Bus service in Tuscany is as well-developed as railways, although it is not so popular as the timetable is not very accurate. But still, bus routes connect main cities and resorts all year round. Tickets are available at the stations. In large cities tickets may be sold by an agency, and in small towns you can buy a ticket right in the bus.
Tickets may be with a seat number or without it. During the tourist season, it is better to buy tickets in advance, so you can get a more comfortable seat.
If you decide to take a tour on a car of your own, then traveling will not be a problem at all. There are many well-maintained roads in Tuscany. On the west coast of Tuscany, resorts from Viareggio to Marina de Carrara are connected by the road which goes close to the resort area. The “Sun Highway” is located on the east coast. The cities of art, Florence and Siena, are connected by a state highway. The capital of the region, Florence, is well-connected with other Italian cities. The distance between cities may be only a few kilometers, but you should remember that the landscape is hilly. That makes the roads of Tuscany twisting and uncommon for residents of flat countries. Numerous roads are well-maintained, which is not surprising as Italian highways are toll roads.
If you come to Florence on a car of your own, keep it in mind that parking in the city is rather expensive. Affordable fees are at the parking lot close to the Santa Maria Novella Station, on Sundays there is no fee at all. Anyway, it is better to leave your car at a hotel parking lot.
You should take care of gas for your car in advance. Many gas stations in Italy close after 19:00; and lunch break lasts for 2-3 hours. Sunday is a day-off. The exception is made by gas stations located on the main routes; they work 24 hours a day.
Traffic laws of Italy are in the frames of international standards, so you are unlikely to have any surprises. Speed limits are the following: 50 km/h for city, 90 km/h for state roads (strade regionale, strade provinciali), 100 km/h for strade statali and 130 km/h for highways (autostrade). Highways are equipped with cameras which take pictures of violators. It's better to know about possible fines in advance. The fine for speeding may be from 5 (over limit by 5 km/h) to 500 euro with driver's license suspension (over limit by 30 km/h). Prohibited parking will cost you up to 10-30 euro (in Rome it can be up to 100 euro), going through red light costs up to 100 euro. Driving under influence may lead not only to serious fines, but also to imprisonment. Even an attempt to give a bribe to a traffic inspector may cause an arrest.
Anyway, the amenities of Tuscany are definitely worth following some road restrictions.