“I wouldn’t do that if I were you.” 「私だったらそれはしないね。」
“If I were you, I’d be careful.” 「私だったら、気を付ける。」
アドバイスする時に、相手がいる状況にもし自分がなったら自分はこうすると伝える事があります。「I wouldn’t do that if I were you(私ならしないな)」はこれから相手がしようとしていることがお勧めできない時に伝えます。第三者についても使えます。「私が彼なら、その日お家に残っていたな。」
We often give advice by saying what we would do if we were in someone else’s situation. “I wouldn’t do that if I were you,” is a way to say that you think what they are going to do is a bad idea. You can also use this phrase to talk about a third person: “I would have stayed home if I were him.”