Paestum is a unique and awesome place to visit. I don't think that there are many other places where you'll find Greek temples surrounded by a ruined Roman town. It's well worth the trip. I do find it interesting though that it's a bit like a forgotten child. Similar to much of Campania, signs and general convenience could be better. The train is quite a distance from the site and the bus is slow going. This information should not discourage, just plan ahead.
Don't skip the museum. There are great frescoes in amazing condition...
To get Paesum, you can have an option to choice a bus of praivete line, it's called S.C.A.T, you pay just 2,50 euro(it's more cheeper then railway) on board, the bus let you get of near ruins, you can get a timetable in Salerno tourist infomation and many lacal people used to take it to go to Salerno, it's convenience solution. Take it at Concordia Place(Salerno city principal bus station) and after 30 min. you can get on the corner of the Paestum ruins.
Pleace don't hich hike in this zone, it's dengerous.
Paestum is on the trainline from Napoli through Salerno to Reggio di Calabria.
The new town is located at the trainstop Stazione di Capaccio, but the ruins are closer to Stazione di Paestum (1 km).
From Capaccio there is 6 km to the ruins, so it is much better to get of at Paestum, but not all train stops here. From Stazione di Paestum, just walk , through the gate in the old city wall in front of the station and walk straight out untill you see the ruins in front of you.
The trainride from Salerno to Paestum takes about 35 minutes, and the train leaves hourly on 42 minutes past the hour. The ride costs 2,90 euro. The ticket office at Paestum is closed for hours for siesta, so make sure have a return ticket or by it at a bar near the ruins.
Here is a map of Italy and the location of Paestum.
Paestum is 40km (25 miles) south of Salerno, 100km (62 miles) south east of Naples, 304km (188 miles) south east of Rome.
Paestum is within easy reach of Salerno, an hour away by train. Both buses and trains service the route. You can catch a southbound train, which departs from Salerno with a stop at Paestum about every 2 hours. For schedules, call 089252200 in Salerno. A one-way fare is $2.50, and the journey takes an hour.
The temples are situated in the middle between train station and Paestum town. And it takes about twenty minutes to walk there along this wall.