The main blue-lined parking areas (paying Mon to Sat) are:
Via San Giorgio (Ducal Palace area) - Piazza Sordello (Ducal Palace area) - Piazza Seminario (Ducal Palace area) - Piazza D’Arco - Lungolago Gonzaga - Viale Risorgimento (Palazzo Te area)
Piazzale Montelungo (Palazzo Te area) is a particular blue-lined parking. Here you pay just one euro for all the day (Sundays too) and the parking-meter machine will provide with two tickets: the parking fee and a bus ticket.
The main white-lined parking areas (always free) are:
Keep following this blog for other tips!
For further information about the Italian parking system, please check this website.