Rail
You have to get down at Mapusa train station:Thivim. Then the cheapest is to take the local bus to Mapusa bus station: Kadamba. - go out of the train station, across the parking, and along the road, if you don't see the bus, ask around. Then in Kadamba, Just ask around where is the bus to Anjuna. It will cost you less than Rs 10 to get to Anjuna from Mapusa by local bus (sometimes crowded)... Or Rs 350 gets you there in an auto-rickshaw
Bus
You'll arrive near Kadamba, or depending on the bus company sometimes directly inside Kadamba