I've been to Tokyo a few times including a trip each of the last 3 years--at first I neither spoke nor read any Japanese (mind, I'm not much better at either now).

For me, having previously experienced public transport in Paris and London, the actual train/subway piece was no big deal. Having a plan of where to go--where you are, where you are going, which train/subway lines go between, and where can you transfer between them--works just like everywhere else. The experience of being in Shinjuku or Shibuya station and navigating in and around, I was not prepared for <mind blown>.

I think getting the Suica card is the single best thing a first time (or any time) visitor can do to improve the experience. By eliminating the issue of figuring out the fare for each trip, you only have to focus on getting there.

Now that almost all stations seem to have signs in English as well as electronic signs in the trains showing the next stops (Yamanote line has these anyway), it is quite painless.

Unless you are in a hurry, and it is rush-hour.