Compare with Google’s currency exchange calculator.
You might want to exchange cash at the airport — although 7-11s and post offices are ubiquitous (the best places to get Yen for foreigners (that may no longer be the case for 7-11's 7 Bank), and easily found on Pocket Earth!), the fees get pretty expensive.
Consider: Your bank’s possible foreign ATM fee AND an international transaction % AND the ATM’s fee (~200 Yen). For example, with my bank, I lose ~$10 if I exchange $100. More on all this, later….
Check your itinerary to see which terminal you’ll arrive in. True to Japanese form, the PDF terminal guide is an adorable, colorful clusterfuck of information — there’s even helpful phrases on the last page! Use an app like GoodReader to save the PDF to your phone.
For anything you want to see in Tokyo, besides just plotting it on a map, make sure you know the floor number.
Unlike many other cities, the best stuff in Tokyo is often to be found off street-level. Or rather, not found, if you don’t know where to go.
Sure, you can come to Tokyo blindly, but it’s a good bet that you won’t see much out of the ordinary and obvious unless you do a little research and plotting.