If you're driving from the south, follow the coastal road, Hwy. 180, from Veracruz. From Xalapa, it's best to do the same: Drive down to the coast and then north.
The quaint ADO station (tel. 784/842-0218) is at the corner of Venustiano Carranza and Benito Juárez, 4 blocks below the main square. Almost all buses are de paso (originating elsewhere), so departure times can be a little earlier or later than the schedule says. Taxis pass in front of the station frequently.
Note: This information was accurate when it was published, but can change without notice. Please be sure to confirm all rates and details directly with the companies in question before planning your trip.