North of the main bus terminal, behind the Church of Santa Faz (the one with a blue dome), is a local stop for buses going downtown. These run along Avenida León Borja, which turns into 10 de Agosto near the train station. Going the other way, take any bus marked ‘Terminal’ on Primera Constituyente. The fare is $0.25.
You can taxi nearly anywhere in town for $1.25. Further points like Terminal Inercantonal run $1.75.