I was reading a post about the field changes and they mentioned working at the box store. And that got me thinking about the liability of giving advice, there and in my own day to day. Are we liable if Johnny Q does what he thought he heard me say and hurts his self?
If you find yourself in that position preface everything you say with "I am just a store clerk" and do not represent anything you say as an official recommendation from a licensed professional. They are not paying you enough for that.
If I'm dealing with someone in the Trades, I try to stay out of court by making them fill in the details of an idea. I don't say "connect those terminals together" I say "Have you thought about jumpering the terminals?" Instead of "you need some shoring in that excavation" I ask "shouldn't there be some kind of suppport on the wall of that hole?" It's not perfect, but it makes it a whole lot harder for a lawyer to win.
As to someone who's totally clueless (think 'Renovation Realities' on TV); I either do the job for them or tell them that it would be faster/cheaper to just hire someone to do the work.