A few best practices for taking photos of couples:
Spend some time chatting with the couple before hand - this allows you the ability to get to know them and find out how they interact.
Ask them if they have any specific photo in mind - this will allow you to make sure you accomplish what they are looking for but then you also are able to take some creative liberties.
Your surroundings matter - make sure you are aware of everything that is in your lens view. This photo is a great example because here we see a few out of place items that I should have photoshopped out.
Spend time following them around a bit, it never hurts to take a documentary style to your couples photography!
I hope these few tips help you take better couples photos. Does anyone have best practices they are willing to share?
Alexandria