Limited warnings

From Warn people about two things by Tyler Cowen, a variant of Hayek's problem of knowledge. Tyler gives an example of a range of possible warnings, which two do you choose?

Driving is dangerous
Fight nuclear proliferation.
Don’t let your kid near a bucket.
Politics isn’t about policy.
Beware the Ides of March!
Some people out there suck!

Not sure about these as specific examples but as a father of three teens where I am constantly finding circumstances where I wish to offer a warning but also being cognizant that too many warnings become background noise, I am very sympathetic to the conundrum of warning under conditions of limitation. If you could give only two warnings or admonishments, which would they be? I might go with:

Pay attention
Think it through

But I sure would like to add a frequent one from our home, "Just because you can do it, doesn't mean you should do it."