Pack weather-appropriate clothing. Amsterdam has hot summers, cold winters, and moderate spring and fall seasons. If you are traveling in the summer, bring a light jacket for unexpectedly cool days, but stick to light layers and warm-weather clothing. In the fall and spring, pack a mid-weight jacket and layers to accommodate changing temperatures. Amsterdam winters can be very cold, so bring warm clothing, a heavy jacket and other winter accessories.
Bring stylish items. Europeans tend to be quite fashionable in general, and Amsterdam is no different. Leave the dirty backpacker clothes behind and bring the nicer items in your wardrobe. Think sleek, fashion-forward pieces that will be comfortable during long days of sightseeing. As a reference, pack items that you would wear on a shopping trip to a high-end store--comfortable, but not lacking style. Don't forget a scarf, which is a must-have accessory for Amsterdam residents and is useful for an unexpected cool afternoon.
Choose activity-appropriate items. Any trip to Amsterdam is likely to involve a considerable amount of walking, so bring comfortable shoes that will support your feet. Also, bring an additional pair to change into at the end of a long day. No matter what time of year you're visiting, bring an umbrella for rain. If you plan to experience the legendary Amsterdam nightlife, pack evening outfits. For day trips into the surrounding countryside, consider bringing a daypack to carry a jacket, camera, snacks and water.
Pack necessities. Before you depart for Amsterdam, be sure to have a supply of any medications you take, and keep them in their original bottles to be safe at customs. Bring a converter for batteries and laptops, but leave behind most electronics, which can be damaged by the difference in voltage--hair dryers are particularly susceptible. Consider bringing a guidebook, which will help you discover important sights and practical city information. When in doubt, opt to pack light; Amsterdam is modern, and you will find anything you need in the city.