Chiming in a bit late now, but from what I gather, the bigger annoyance today seems to be English tourists. Things generally frowned upon:
1) Wandering the streets without looking around. The streets are narrow, and on the right side of each car lane is a bike path. Cyclists consider themselves to have right of way in every situation and will not necessarily slow down much, opting to slalom between crossing people and swearing (usually by means of wishing a disease from Biblical times upon you) at the ones that get too close. Walking in a tight row of 3-4 people that obstructs the whole street is also a pain in the ass.
2) Tolerance for soft drugs doesn't mean go crazy. Just like being shitfaced-drunk and pissing onto a parked car, being retardedly stoned or tripping balls on truffles in public is frowned upon. Most places in the service industry seem to have an extra supply of patience for stoner tourists that take a minute with their food order, though, so it's okay to be stoned - just don't be a nuisance. Also, behave around children. Smoking weed outside is illegal but quite tolerated, but locals will appreciate if you cover your joint as you bypass small children. The Dutch are very aware that their legal environment is more tolerant than most, and are quite willing to extend it to visitors - but they expect you to be as responsible with it as they are. They have little patience for fucking around when the rules are already so lenient.
3) Being loud - goes together with not controlling your intoxication. I think this is obvious anywhere.
In general, though, Amsterdam has some of the rudest customer service I've ever experienced. They deal with annoying kids that smoke weed for the first time on a daily basis, and it's a very busy city, so don't expect too much politeness. Tipping is standard practice and not leaving a tip is indicative of bad service (and will probably get jeers and bad looks if they did nothing wrong) - this shouldn't be a problem, coming from America, though? You guys tip, don't you?
Also, prepare for the fact that anywhere from 30-60% of the people you come across will not be locals. There are tons of expats and other tourists both wandering the streets and working as budtenders in coffeeshops. Asking for directions is a nightmare since only the third person you ask will actually be from Amsterdam.
Oh, and many coffeeshops insist you remove your hat (so you are identifiable on surveillance camera). You will probably not be asked to do so, but told very aggressively, as if you had already been warned once or twice. Consumption is also mandatory, so you must at all times have a drink of some sort underway (and order a new one as you finish). In many coffeeshops, to be seated you MUST buy cannabis from that coffeeshop.
