1. DON'T GET WASTED. "But... but that's what I'm coming for!" I'm pretending to hear you cry. And you have a good point. A very good point. But this is my point: everything is stronger here. The beer, the weed, the
2. DON'T GET RIPPED OFF. That shady guy on the outskirts of the Red Light district offering to sell you E's and coke, who looks like a rip off merchant? He's a rip off merchant. And Class A's are as illegal in Amsterdam as they are anywhere so you have no recourse when you do get ripped off. If you really must indulge in actually illegal chemicals(and there is honestly no need), go to a club and try to spot the guy who looks like a drug dealer. He's a drug dealer.
3. DON'T EAT JUST ANYWHERE. Food in Amsterdam can be hit and miss in quality and often very expensive. All restaurants have menus outside so be sure to check them out before entering. There are lots of restaurants with "tourist menus" grouped around Centraal Station, Rembrandtplein and Leidseplein, especially Korte Leidsedwarsstraat and Lange Leidsedwarsstraat which are lined with cheap and tasty international restaurants, and where you can get a 3 course menu for under 15 euros a head. Fill up there. You can save quite a bit of booze 'n blunt money by picking up breakfast and lunch from any of the ubiquitous sandwich shops and fast food restaurants.
4. DON'T ABUSE THE LOCALS. They all speak English better than you do, even when they pretend they don't. Most importantly, do not abuse the cops. The cops in Amsterdam are, ordinarily, surprisingly pleasant, helpful and tolerant. They will, however, kick the absolute shit out of you if you attack them. Don't come across as a scumbag lager lout and get yourself arrested. Also, the right wing coalition government is seeking to cut down on the sex and drugs tourism. Don't give them more reason to do so. Crap like homophobia, racism and sexism may fly in whatever 1950's backwater you crawled out of but it isn't tolerated here and you'll be the weird one that everyone is giving a wide berth.
5. DON'T SKIP THE TOURIST ATTRACTIONS. Seriously. You may not give a crap about the Anne Frank house or care for standing in a queue to see a bunch of paintings by a mentally ill bloke but Amsterdam is a unique and beautiful city and wandering joint-in-hand around cobbled streets and towering narrow canalside buildings finding little parks and statues beats blowing smoke out of a hotel window, hands down. There is a wonderful atmosphere here. Suck it up.
6. DON'T GET HURT. Watch out for the bikes, the trams, the canals. Bicycles are everywhere, mostly coming straight for you. Figure out what is a bicycle lane and don't walk in it unless you are a bicycle (hint: if you are reading this, you are not a bicycle). If you hear what sounds like a bike bell ringing, look around to see where it is coming from and step out of the way. The same goes for trams, although they'll be slightly easier to detect and will hurt more when they hit. You do not have right of way over either of these and it's more difficult for them to stop than it is for you to move out of the way. Stay on the pavements and be alert on corners or when crossing roads. As for the canals, they are not fenced off. You can easily fall in, especially when you're merry. No good holiday story has never ended with the words "...and that's how Joe drowned".
7. DON'T COMMENT ON ZWARTE PIET. Just don't.