Hmm, I would probably start them off with a show that's really enjoyable and depending on their preference if it's going to be a Subbed or Dubbed show.
If they would like a subbed, I would suggest them: No Game No Life or Tokyo Ghoul
If they prefer dubbed, either: Fullmetal Alchemist or Death Note
Something like that anyway. I just ask them some very 2 or 3 easy questions and base it off that.