The main transportation hubs for the Amalfi Coast are Naples, Sorrento and Salerno. The principal forms of public transport serving the Amalfi Coast are Sita coaches and, in the summer, the ferries and hydrofoils run by the Metrò del Mare navigational company.

The nearest airport is Napoli Capodichino, from the airport the most confortable and easiest way to reach Positano is by taxi especially if you share in a group as the coast is likely to be less than getting a taxi to the main harbour to get the Hidrofoil to Positano or the ferry to Sorrento (then another taxi or bus to Positano).

I would not recommend hiring a car as it is not really needed in Positano and parking is expensive. If you need to do day excursion you are better off with public transport or taxi.