The law and the coffeeshops
Not for sale Although the use of softdrugs is allowed, the shops are allowed, having more than 5 plants for own use is not allowed. So growing your own plants (more than 5) and sell to a shop forbidden. In this way a strange situation appears for a coffeeshop: you are allowed to sell, to have in stock (small amounts only), but you cannot purchase to sell the "herbs". In theory this is strange. In fact, the shopowners are very aware of their status, en will be very discrete. Most shopowners try to be good shopowners, that means don't cause trouble (openinghours, IDrequests, noise etc).
Grey
Advertising is not allowed, and no new shops are opened. Actually, when a owner sells a shop, a new starter is not allowed to sell softdrugs. No licence for that will be issued. (Probably Amsterdam has a lot of grey shopowners within 30 years ;-)
Get drunk or get stoned, but don't do them both!