Helle and Alex, pre wedding shot.

1. No Awkwardness! On the day they know you, and you know them. Let's face it, when you meet with a couple for the first time the first hour is a bit awkward and by meeting with them beforehand you don't get that period of uncomfortable silence and small talk about the weather on the actual wedding day. This is also important for you as the photographer, because it takes off a bit of the nerve on the day allowing you to keep focus and gives you the confidence to direct the couple during the shoot.
2. Expectations! To find out what the couple expects from you and from the shoot, what style they like etc.
3. Location! To find some great locations, so you don't have to waste time scouting on the day.
4. Schedule! To find out what their schedule for the day is and how much time you have, and also make them understand that the time-window sets the limits for how elaborate photos you can do or how many locations you have time for. 
5. Test Shots! To take test shots of the locations, so you can pre-think each setup and possible compositions.

Below is some of my favorite final shots from the wedding day.