make him look good, him is used incorrectly. It's better to say himself
Then the statement would be,
Fashion Sense
My younger brother Sergio applied for a job selling retail electronics at the mall. Good thing I was home on the day of his interview. As he was walking out the door, I had to stop him. He was wearing a light-green shirt with orange suspenders. Sergio was supposed to make himself look good for the interview. Instead, he looked like a circus clown. I insisted that he change his outfit immediately.