You'll need big cash as it's London prices in da dam.
Top tips here from a frequent dammer: -
1) Avoid FEBO - it's like an ATM for food and should only be attempted if you are absolutley slaughtered and the kebab shops are blatently serving pedigree chum.
2) Keep you wits about you when crossing the road - pedestrians are after trams, trucks, vans, cars, motorcycle, cycles, unicycles, scooters, rollerskaters.......... in the pecking order and people will not stop! Be particularly careful near Centraal Station as at points you have 4 tram lines, 4 road lanes and 2 cycle paths to cross in one go and a green man does not guarantee a pulse on the other side of the road.
3) As said before, only buy hash and weed in the coffee shops and never buy from the ones near centraal station or in the red light district as it's over-priced rubbish. Get yourself away from the damrak and down to liedsplien (ask for Leicester Square - they'll know what you mean).
4) Get a copy of rough guide to amsterdam if only for the maps as they really do help you get around.
5) This should be your coffee shop hit list:-
a) De Rockerij (The rockery - down a side street near Liedsplein) one of the few coffe shops that you can have a beer in.
b) Global Chillage - best hot chocolate and whipped cream n the whole of Amsterdam and the best place for resin fans;
c) Abraxas - egyptian theme with sofas and great coffees for a nice chilled aftrenoon;
d) Homegrown Fantasy - just for the toilet (you'll know what i mean when you get there just don't be too mashed when you go)
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e) Kashmir Lounge (if you can find it). Beyond Vondel Park and then some this is the finest chillout coffee shop in da dam and is frequented more by locals than tourists. As such drinks are very reasonable and the weed is very competitively priced.
f) Avoid Bulldogs like the plague unless your idea of fun is cheasy pop hits and being puked on by boozed up brits who can't hold thier drink and have no concept of how to behave in someone else's country.
Last but most definitely not least, have some respect. Don't smoke gear on the streets as it's just darn rude after they have given you all these wonderful places to smoke. Also, doing so can land you in hot water with the law as it may be tolerated but it's still illegal to smoke cannabis outside of the coffee shops (although you'd pretty much have to run full pelt into a copper and have a kilo of weed fly out of your pocket to get in any real bother). The Dutch are wonderfully friendly people and are very welcoming as long as you don't run around wearing a "Where's the weed?" T-shirt grinning like a raving lunatic - you're not American after all.
Have fun!