There are several bus routes from various cities, but most traffic is from mainly Mumbai and Pune. Due to increasing demand from the south, there has been an increase in buses and trains from Mangalore, Bangalore and New Delhi. Overnight buses from Mumbai to Goa are an alternative to trains and flying. Book in advance during the crowded seasons (particularly during the Christmas-New Year rush, for Carnival, or when other Indian regions have school holidays when families travel).
Kadamba Transport Corporation is the Goa state-run transport service. Its buses have seen better days, and more efficient times. There are also other state-run buses run by the governments of Karnataka (some services are efficient, specially the Volvo buses), Maharashtra, and Andhra Pradesh. Many private players also offer bus connections to other cities, with varying levels of discounts and efficiency, with the two usually being inversely related.
The main centre for booking train and bus tickets, in Panjim, is around the Kadamba inter-state bus terminus. Tickets for the Konkan Railway can also be booked here, though expect long queues during the holiday season (which in India, can also coincide with the timings when children have a school break).