Just three things.
Dont start smoking too much skunk from the first day you arrive.In 4-5 days you will be like a zombie.Try to smoke when you want to,not every half an hour.
Beware with mushrooms.And when i say it,i mean it.Beware with dried hawaiian.If you are not an experienced user,dont touch them at all.Eat some fresh mexican or colombian.When you go to the smartshop,you better listen to the guy working there and ask for advices.He knows better than you.
Dont miss Vondelpark.