Going from Santa Teresa to Nosara (or the other way around) is a seriously long journey. You will need to start early on either side.
From Santa Teresa you can either take the 6am direct bus to San José and be let off in Puntarenas (you will have to pay full fare of 6500C for this trip even if you only go to Puntareans) or you can take the local transportes Mal Pais bus to Cobano and connect with the 7am direct bus Paquera(~1000C+1800C). Get on the ferry. Once in Puntareans you either need to take a taxi to the bus station (about 16blocks away) or you can walk (check the map for the route). I recommend finding another traveller and sharing the 1500C taxi.
From Puntarenas you will take a bus to Liberia. There is a bus that leaves at 11am. If you made the 9am ferry sailing then you will be able to roll up in front of the Puntarenas station just in time for this bus. Then from Liberia you will take the bus to Nicoya this bus runs every half hour.
From Nicoya you need to walk to another station about 5 blocks away (see map on the Nicoya page) where you will find busses headed to Nosara (and Samara if you choose) and then the bus to Nosara from there. You should be able to make it onto the 3:30pm bus but if for some reason you miss this one, have no fear, there is a 5:30pm. This final stretch is about 2hrs.