Take a free map of Florence at the tourist information. It is good for orientation purposes and includes the location of the main museums and monuments.
Florence has a few tourist information offices all over the town. One is located at the Plaza Stazione near the church of Santa Maria Novella; another one is located at Via Cavour near the Palazzo Medici Riccardi.
Miscellaneous: A map, obviously, is a necessity. After all, you wouldn't want to end up like I did :( (Sorry to say that Lonely Planet Italy's Florence map wasn't much help to a dodo like myself).