Your best option is to WALK!
The city centre of Florence is extremely pedestrian friendly, and with the Duomo in the centre all the major attractions are only at a 5 to 10 minutes slow-walk away. This is how most people move about the city. So I would say walking is highly recommended in Florence, and you will experience such a great small-town feel and atmosphere wherever you go.
Plan B - Bus
But there are public buses too - and you will notice that many of them are tiny mini buses - that can get you around the city if you decide not to walk all the time. Here is an overview of how to use the public bus system in Florence:
Single ride tickets only cost 1.2 euros. A ride is counted as 90 minutes and allows you to hop buses and trams any number of times during that period.
Where to buy tickets
There are several places where you can purchase tickets for the bus system of Florence:
In Tabacchi (tobacconists) and newsstands
You can purchase your tickets from any shop or stand that is signposted by a brown sign with a white 'T' on it
From a ticket machine
there are ticket machines located near parking meter kiosks around the city. If you buy tickets from these machines you do not need to validate your ticket on the bus
On the bus
you can buy your ticket from the machine once you are on the bus, but it will cost you slightly more than buying it in advance. This also automatically validates your ticket
Use your Firenze Card
if you have purchased a Firenze card with the unlimited travel option then you can use this to get on and off the bus lines.
How to use tickets
To use your ticket, it must be validated either at the time of purchase or on the bus itself:
Once you have validated your ticket, they are valid for 90 minutes (80 minutes if you purchased a ticket at a ticket machine), and in this time you have unlimited transfers. Remember to stamp your ticket at your last stop as you get off.
If you have purchased your ticket in one of the stores, make sure you stamp it when you step onto the bus
When to use the bus in Florence
Almost all buses run to, from, or through the Piazza Stazione, which is right next to the main train station. Although most of the city centre can be reached on foot, it could be useful to get to and from your accommodation with your bags.
If you are tired or with kids
Most of the main bus lines run by Ataf will take you out of the city within four stops, but if you are wanting to use buses to get around the city centre you will want to be using the minibuses.
The minibuses are the ones that are marked C1, C2, C3 and D, and they will take people to all the major tourist attractions in the historic centre (even if they take a slightly longer route to get there). For the most part, these will be unnecessary for exploring the city centre, but they are a great option if you mobility impaired or are with children that can't walk as far
For Piazzale Michelangelo
Taking the bus might also be a good option if you are wanting to go to Piazzale Michelangelo but are not wanting to walk 30 minutes each way from the Duomo. You can take the number 12 or number 13 bus lines to get there and avoid the uphill climb.
Information on the bus lines can be found here.
Cycling around Florence is a great idea as most of the attractions are close to one another. Not only can you get to your favorite spots faster, but, since there are many bike paths around the city, you can also ride your bike around some of the most scenic neighborhoods of Florence.
You can rent a bike from one of the rental stands outside the Santa Maria Novella train station for €10 a day.
Florence has no tube. The only company that can drive you around in the city center is ATAF. One single ride costs 1.40 euros, but only if you buy the single ride. There are many options that will make you save money, such as 20 rides cards. There are many lines that will bring you easily from a part to the other of the city.
Via the Google Play Store (whether you have Android) or the Apple Store (whether you have an iPhone) you can check out the app called “ATAF”: there you can find real time schedules and all the infos on the lines.
In these days they’re finishing new lines of the new tramway. They plan to finish around 2019. I predict that when it will be finished, it’ll be even easier to move around Florence.