My approach to weddings:

Freeze!!  This is probably what happens to most people when you have someone with a giant lens pointed at you.  My non-abrasive personality usually comes in handy in these situations as my selective amount of posing and a constant search for those moments between the couple.  The most important thing is to allow people to simply be themselves and capture the moments when they are enjoying themselves.  That is pretty much the only thing that matters.