A stream of buses flows between La Laguna's Intercambiador Laguna Bus Station and Santa Cruz. Bus 015 (€1.45, 25 minutes) is best, as it'll take you straight to Plaza España. Buses 101, 102 and 103 also offer a regular service to Puerto de la Cruz (€4.10, one hour). If La Orotava (€3.15, 1½ hours) is your next destination, take bus 62.
The very handy tram system (www.metrotenerife.com) also links La Laguna with central Santa Cruz, with a one-way ticket costing €1.35 (the journey takes around 40 minutes).
Finding a parking space on the streets of La Laguna is migraine inducing. There’s an underground pay car park beneath Plaza San Cristóbal, but if possible come on public transport.