Oh simply be polite and most of all have a sense of your surroundings/situational awareness, i.e., don't get in the way. You probably want to spend as little time in the main "downtown" area (roughly central station to the Rokin) as possible.
Although everyone under 80 years old speak near-native English (I exaggerate), you'll endear yourself by learning to say good morning, good evening, thanks, and please in Dutch and to start conversations by asking "Is English ok?" in Dutch.
Basically just don't be a jerk and the native Amsterdamers will happily take your holiday money.