Legalise pot and MDMA. Tax and sell with government control.
Legalise cocaine and opiates and strictly medicalise their distribution. This will make them cheaper, safer and far less glamourous.
Leave seriously nasty crap like meth and crack illegal. Since these are either easily homemade or a derivative of cocaine the trick here will be to try to shift addicts to medically controlled opiates and cocaine. From there their addiction can be more easily managed.
Of course the devil lies in the details of such proposals, but the "system" in place at the moment is clearly not working...
That is all!