By ship
There is a network of ferries that run along the towns of the Amalfi Coast. The ferry service is run by Coop Sant'Andrea (http://www.coopsantandrea.com). They provide quicker access to the towns during the summer months, as opposed to the one main Amalfi Coast road which connects Amalfi to Praiano to Positano and onwards to Sorrento. Major ferry stops are Salerno, Sorrento, Positano, and Amalfi. In summer, there are ferry connections from Positano and Amalfi to the pretty towns of Maiori and Minori. Praiano is not serviced by ferry as there is no stable pier to dock and ultimately the marina is very shallow. Positano is the closest point for people staying in Praiano who want the ferry.
By Train/Bus
Main train line of Trenitalia closer stations are in Naples Piazza Garibaldi or Salerno main station.
From Naples use the Circumvesuviana local train to Sorrento, trip is circa 1 hour (http://www.vesuviana.it) and then continue to Praiano by SITA bus (http://www.sitabus.it), trip is circa another hour.
From Salerno use the SITA bus (http://www.sitabus.it) to Amalfi, trip is circa another hour. the continue to Praiano, still by SITA bus for about further 20 minutes.
By bus
Use the SITA bus (http://www.sitabus.it) from Sorrento Circumvesuviana train station (http://www.vesuviana.it) or from Amalfi bus station. From Sorrento the trip takes 1 hour circa, from Amalfi there is a 20 minutes drive.