Decide when you want to leave Amsterdam Central Station. There are 14 daily departures, giving you plenty of options. Ranging in overall time from 11 to 19 hours, there's definitely a train to suit your itinerary.
Consider booking a first class ticket. With a trip this long, you're going to want to be as comfortable as possible. Given that you might have to change trains up to 5 times, you're going to want to make the traveling as painless and easy as you can.
Use your status as a student to get a great discount on tickets to Prague-Holevice. You'll also find that small children are free, while children and adolescents up to the age of 16 get significantly reduced fares.
Pay for your tickets online using a North American credit card. Alternatively, you can also go down to the Amsterdam Central Station to book your tickets to Prague before you leave.
Make sure you have your tickets before you leave. The best way to do this is by booking online at the Netherlands Railways website and having your tickets sent to your home address or by having them held at will call in the Amsterdam Central Station.