Simple!
From the airport: the cheaper journey is long, of course, and I can’t stand it. I normally buy an express ticket to Ueno from Narita airport. Most machines have an english option, so it really is easy. If you need to ask someone, just use the most basic English you can, with hand signals! Note that many words are English in the first place e.g. Express!
From Ueno, get yourself a PASSMO, or SUICA card. I used PASSMO. It works like many top up cards. Just fill it with cash and swipe away to get through gates – you can even use it at certain shops or vending machines.
http://www.youtube.com/watch?v=fw5Xj2MLiZ0
More info:
Tokyo Metro English Site (get the latest subway map from here)