Even if the advice was given nicely, people overreact to it badly.
"I know how to play my job." Is the most common response I get.

They didn't ask for an advice in the first place.
If they are doing it wrong, I'll tell them how to fix it.

The bad thing here is forcing people to do something. Don't repeat what you said more than once.

I usually ask people to do something followed by explaining why it is better.
If they don't do it, fine. At least I tried.