The back of this dress is seriously my favorite because of the exposed criss cross design but it is also hard to wear a bra with it so I'm glad the shirt under a dress style is a thing for now.
You can definitely wear short sleeved tees under instead of long sleeves like I did but I think high necklines is what you should be looking for when styling your tees with the slip dresses. You don't want the necklines to be too low and distracting from the dress' neckline.
Another fun way to wear velvet is to find similar colored tops and bottoms to make them into a two piece set. Off shoulders are so girly and velvet just makes it all the more classy.