Tokyo Metro distributes a convenient pamphlet in English, Korean and (standard and simplified) Chinese to useful for sightseeing in Tokyo. It contains useful information, such as a Tokyo Subway Route Map, how to ride the subway, convenient discount tickets, sightseeing routes and simple Japanese phrases used when riding the train.
The pamphlets can be found at Narita Airport Terminal 1 and Terminal 2 (at the Tourist Information Center (TIC)) and most Tokyo Metro Stations. There are a few exceptions where it is not available. They are as follows: Kita-senju Hibiya line station, Naka-meguro, Nakano, Nishi-funabashi, Yoyogi-uehara, Wakoshi, Meguro and Shibuya stations.
You can download a PDF copy of the Tokyo Metro Guide here.

If you do not have Adobe Reader, you can download it free here.