As soon as you can, Get a (Free) Subway Map.
Do Not Count on ANY map you have.
Since July 22nd, 2001 there are some Major Changes.

When you in town it is best to use "Manhattan Block by Block: A Street Atlas".
ISBN: 1878892126. Author: John Tauranac. List Price: 14.95$ + Tax.
It is an excellent tool to use. Go to the closest book store.

Coupons for Macy's sales & others: Buy the local newspapers:
The New York Post, The Daily News, etc. The cost 25-75 cents.
The coupons are not less than 10%. When you purchase anything 10$ and up...
You already saved something.