The best harm reduction strategy has to start with legalising cannabis. Ignoring this truth has caused most of our problems.
Education programs have to be evidence based to be credible and trusted. If the truth about cannabis isn't told, all other information becomes suspect.
The continued prohibition of well-researched and relatively harmless cannabis has led to the proliferation of synthetic products. That they were for sale in shops made them appear safe to young people. Many of these products exhibited nasty short term effects and all have unknown long-term outcomes.
Legislative approval of these other substances, and calling them "legal highs", looked like cynical profiteering, at the expense of cannabis users, by everyone involved. That they were subsequently, effectively banned has only made matters worse, as you rightly pointed out on The Nation, Russell.
Any national drug strategy which doesn't include legal cannabis is a waste of time and doomed to fail.