Help with head movement

Hello everyone, I have come here to the Developer Forum on this day to ask about a question that’s been bugging me, and I haven’t found any reliable answer…

So what I’m trying to do is, make a script for ONLY characters, not the players avatar, that can move your head towards the direction you’re facing. BUT, I want to make it so that if you’re looking up, your head only moves slightly upwards, and if you’re looking left or right, it doesn’t go beyond that point, (In real life, were that to happen, you’d probably end up with a broken neck), so that you don’t end up with your head facing behind, that’d be cursed. I meant no offense about the death part though, please don’t take it as offensible.

Anyways, I’ve tried some tutorials, but none gave me the satisfaction of a job-well-done when I tested them out. I don’t want the torso or anything else to move, just the head.
I hope one of you can help me out. I’m not asking for a full script, but I’m not much of a scripter myself anyways.