Tequila is about 60 km northwest of Guadalajara, and getting there is straightforward.
By bus. Local buses run from Guadalajara's old bus station near Parque Agua Azul every 15 minutes or so throughout the day. The journey takes around 90 minutes and is the cheapest and most practical option for independent visitors.
By car. The drive from Guadalajara on the Guadalajara–Tepic motorway (highway 15D) takes about an hour. Parking in the town centre is available but can be tight on weekends. A designated driver is obviously the sensible approach given the purpose of the visit.
By train (tourist). The "Tequila Express" is a tourist train that runs from Guadalajara on weekends and includes food, mariachi music, and tequila tastings. Note that it actually stops at Amatitán, the base of the Casa Herradura distillery, rather than the town of Tequila itself — enjoyable, but a different experience from visiting the town. Check current schedules with the Guadalajara Chamber of Commerce, which operates the service.