Make sure all the scheduled maintenance is done on time.
If you don't have a service history on the car, or if it's never been done before, change the timing belt and water pump. These are every 90K miles or every six years, whichever comes first.
Get the Dali Racing "window fix-it thingies" unless you know that the window regulators have been replaced. This will prevent an expensive repair.
Keep it clean and waxed.
Read the manual.
If you plan on doing any of the service yourself, get a copy of the service manual.
There is more information on many of these items in the FAQ on this site.
Get together with other NSX owners (through the NSX Club of America as well as these forums). Part of the fun of owning it is participating in activities with other owners.
Enjoy your car!