Make sure the suit looks like it has been bought in the last 10 yrs and not a fashion extreme. Nothing worse than seeing someone turn up in :
a: A WIF (weddings, interviews & funerals) suit that is pure polyester and too tight / flared / has the sleeves rolled up a la Miami Vice.
b: One of those black suits with a mandarin collar!
Oh - NO comedy tie and make sure the shoes at least look clean!