When you know your thing might be received negatively, inoculate the reader right at the front.

This will make them more open to receiving it.

For example, say "What I'm going to say will sound cynical, but I think it's actually optimistic. By understanding how the system actually works, with clear eyes and without judgment, we can see how to steer it to great outcomes."

Now later, when you say something cynical, instead of them saying "this guy sounds cynical," and tuning out, they say "well he did say he'd sound cynical, so I'll keep listening"

You've effectively capped the downside of people disengaging from your argument, but preserving the upside.

If the person agrees with your warning, they'll think "well he did tell me, at least he's self-aware about it."

And if the warning was unnecessary because they agreed with what you said, they'll forget about the warning.

So the warning has no downside and significant upside.

That means the best practice is to imagine what the negative reaction is that listeners are most likely to have and explicitly inoculate that.