"If I were you......"
You should tell Kylie that you lost her maths homework.
If I were you, I'd tell Kylie that you lost her maths homework.
Why don't you say sorry to Parker for scratching his new bike?
If I were you, I would apologize to Parker for scratching his new bike.
You shouldn't play baseball near Mr. Lopez's house.
I wouldn't play baseball near Mr. Lopez's house if I were you.