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.