Florence is best explored by foot as most of the attractions are within walking distance. However, if you need to go further, you can take the ATAF bus system. A single bus ticket costs €1.50 and allows for 90 minutes of travel. Taxis are also readily available but can be expensive.
If you have more time, consider visiting the Accademia Gallery to see Michelangelo's David statue. If you have less time, skip the Bargello Museum as it can be time-consuming.