Some things I would watch out for:
Taxis. If you take a Taxi everywhere you go, your money will drain pretty quickly. The Subway system and local trains may seem intimidating, but it is pretty simple once you are actually there.
Jeans. I bring this up because you mentioned buying jeans. I bought a pair of jeans in Tokyo last time I was there and they are the best jeans I have (quality wise and stylish) but they also cost around $160. I wanted several other pairs of jeans while in Japan, and several of them exceeded $200 or $300 each. Just don't buy too many and you should be fine
