Visiting Amsterdam requires, like all European capitals, comfortable and practical clothing. A casual look and comfortable shoes are a must: sneakers for getting around the city on foot are perfect.
Depending on the season chosen for the trip, the contents of your suitcase can change drastically. In summer the temperature is rather hot so during the day light clothes, shorts and T-shirts will be fine. In the evening you'll want to cover up. Spring is mild but rain is to be expected. So a big yes for mid-season clothes, cardigans and trench coats are essentials.
Summer in Amsterdam is the festival season, this is by far the most beautiful time for those who love being outdoors. During this period you can't go without t-shirts, tanks and crop tops. As for the trousers issue, make sure to pack both shorts and jeans for the colder evenings. Here's a little inspiration for you