If you're going Sightseing, I strongly advise the Iamsterdam card. You get free transport around, you get free entrance in a lot of things, and like 50% discount on others.
http://www.iamsterdam.com/en-GB/experie ... -city-card
Now about places I remember seing (4 years ago)
House of Ann Frank, is an historic mark that people will ask you about
Dinner at a boat in the canals, should come free with the Iamsterdam card
The botanic garden, is a bit out of hand but, it has a lot of crazy ass plants
The Van Gogh museum is also terrific
To be honest that's about the only things I remember from the card. Tough the card allowed me to spend entire days running from one side to the other to see things. It pays off. Oh and don't go for 1 day, you don't have time to use it well then. Also, bear in mind that some things you only get 50% or 30% discount with the card, so try to do the free things first. Even if it doesn't look great sometimes, I often got surprised.
I suggest you enter a coffee shop, I myself don't do drugs but, you just have to enter one and look at their menus and take pictures.
If you're going with a partner, I suggest you try Space Cakes one day before going to the hotel
(one is plenty imo, but then again, I don't do drugs). They come in a package with instructions, make sure to read them.