THIMUN offers a pick-up service to and from Amsterdam-Schiphol Airport to your hotel, the Convention Center or the Stayokay Hostel. For further details, please see the relevant order form (which you can download here).
For those not using the Pick-up Bus Service, there are frequent trains direct from Amsterdam/Schiphol Airport to The Hague. From Station Den Haag Hollands Spoor (HS), tram 1 (direction Scheveningen) takes you to the Crown Plaza Hotel which is a few minutes walk from the Convention Center.
From Den Haag Central Station (CS) tram 16 (direction Statenkwartier) or bus 24 (direction Kijkduin) will take you directly to the Convention Center.