Amsterdam is quite a small city. I think the whole of Amsterdam is the same size as the centre of London or Paris. So the city centre is not that big and that means it is a great city to go by foot. You can easily walk through the city from east to west in less than an hour. Almost all the hotspots (and spots that are not that hot but really interesting to see) are on walking distance from each other. You can stroll around yourself, or join a city walk tour. See also these walking tours.