At this service shop you can get information about public transport and buy tickets.

You can buy your OV-chipcard here, and have it activated for use on trains and local public transport, plus you can load money onto it.
Furthermore, there are touch screens (also in English) where you can plan your route to a destination. You can then choose between public transport, walking or cycling.
You print the routing advice for free.

This shop opened in June 2015. Special about it is that the staff can answer all questions about all public transport in and around Amsterdam.
This covers therefore not only the trains, but also Amsterdam buses/trams/metros (run by GVB) and regional bus lines (bus companies can change every few years).

The shop is located in the IJ-hal, which is the large hall at the far North side of the station.