One of the challenges of weddings is that there are often people going everywhere – including the backgrounds of your shots. Particularly with the formal shots scope out the area where they’ll be taken ahead of time looking for good backgrounds. Ideally you’ll be wanting uncluttered areas and shaded spots out of direct sunlight where there’s unlikely to be a wandering great aunt wander into the back of the shot.
Read more on getting backgrounds right.
One of the great things about digital photography is the immediacy of it as a medium. One of the fun things I’ve seen more and more photographers doing recently is taking a computer to the reception, uploading shots taken earlier in the day and letting them rotate as a slideshow during the evening. This adds a fun element to the night.