First of all I like to recommend that, if at all possible, when planning your trip attempt to be flexible as to when you wish to go. It used to be that an airlines tickets for cheap flights were published at your local travel agency. The best time to visit the city is probably between late September-November, so book your tickets well in advance and you can get heavy discounts on your air fares. There’s no bad time to book a flight to Amsterdam, but for cheaper flight tickets and fewer crowds, any time outside peak season is favorable.
Cheap …