Six years ago, I wrote a column comparing IT managers' prohibitions on using your own devices and applications to abstinence-only sex ed: a high-handed approach that leaves its audience ignorant and resentful, and dedicated to undermining you behind your back.
An outstanding piece on Reddit by Thebananaking makes the same point in a series of bulleted lists, extending the parallels into how you react to your users/kids when they get themselves in trouble, and the benefits of encouraging their independence from you for day-to-day tasks.
Don't rely on technical solutions to administrative problems.
If you lock them out of things, you just encourage them to work around your restrictions.
Use technical solutions as a backup – but your first lines of defense should be policy, supervision and a review of the needs driving the problem behaviour. What are they seeking, and why aren't they getting it from what they are allowed to do? How can you provide it in a safe and appropriate manner?
Don't rely on security through obscurity.
If the only thing preventing them from doing something is not knowing about it, you are fucked. Not only will they find out, but they'll find out from exactly the kind of people you don't want them learning things from.
Tell them about it, and then tell them why they shouldn't, so they can't get blindsided or scammed. Tie it into the policy-and-supervision methods above, and you've got your best chance of controlling the outcomes.
Parenting is a lot like sysadminning… [Thebananaking/Reddit]