It is vital that we work to a few golden rules. Always work in a small team. Keep a very low profile. Only deal with people who come recommended. And it's like selling anything else: washing machines, hand made shoes, blowjobs. As long as you don't take the piss people will always come back for more. And that is not to say we don't have that special kind of magic that makes two kilos into three. But never be too greedy.