For getting from Narita to Nakameguro, it’s just next door to Shibuya, so probably best to follow the advice in our article here:
Then Nakameguro is a short journey on the Tokyu Toyoko line (1 stop on express, 2 stops on local train). Or you could just take a taxi (probably cost you ~1000yen)
Absolute cheapest (and one of the easiest) ways to go is to take the Access Narita bus (runs every 15 mins, I think - you can check on their website) from the Airport to Ginza (don’t get off at Tokyo Station), and then take the Hibiya Line directly from Ginza station to Nakameguro. The bus will cost you Y1,000 and the train Y200. Half price for kids.