Hmm... well, I suppose they should really explain what each drug does. Some drugs might not be that bad (like psychedelics or even weed) but will absolutely impact brain development in teens. I think that should really be the main focus. Tell them what drugs are really bad, deadly, have highs that might totally ruin your life because you'll spend forever chasing.
D.A.R.E doesn't really do a good job. I don't know how prominent they are these days, but back in the late 90s/early to mid 2000s before I was a teen, they basically were not realistic or specific about anything. Just "drugs are bad, don't do them." "Weed is like heroin" just a bunch of shit. A lot of teens will see through that, I mean so many movies sensationalize something like marijuana, hell, I personally only decided I wanted to smoke weed because of The Breakfast Club lol.
They made it look so fun and then all these kids who were totally different end up opening up about their worlds. I'm glad I didn't start right away, I was 17 and 4 months which was late compared to most people I went to high school with, many started around 14 or 15 but not that many were smoking all the time. I still think that's too young though, I went through months of severe depersonalization and derealization because the shit was just so strong and I was facing joints because that's how they did it in the movies right?
I'm kinda getting off topic but yeah in the end, I think parents really need to sit down with their kids and talk about what all the drugs do, what it leads to. Show some pictures of meth addicts with faces full of cysts and missing, fucked up teeth. Tell them about bad trips and how some people can get permanently screwed up by psychedelics, they aren't playthings. Lots of teens try psychedelics thinking they'll just go to looney tune land, hell, even I was that ignorant about them until around the time I'd tried them (by then my friends and I discovered this forum, erowid, trip reports on YT) and understood better.
So yeah, in the end, parents need to be honest with their kids about what all these drugs do, which ones are really bad, and why even the not so bad ones aren't good for their developing brains. I've seen so many bright kids start smoking around 13 or so and they end up total burnouts by 15, like it's definitely not good for teens to be getting high even if some of us did and seemed to turn out fine (I'll never really know as my short term memory was always total shit anyway). The depersonalization/derealization was seriously bad though, I don't think that would've happened if I'd started in my early 20s or something. Hell a lot of people suggest you shouldn't even do it until 25. I think 17 is fine, personally. I think I've read the brain is like, 80% developed by 17-18, but that's still not full.