Go for variety
Vary your subjects to create an interesting range of images. Focus in on details such as the decorations or food laid out beautifully, photograph people as they arrive, and then go for more candid shots as the night unfolds (if you last the course, try shooting again when it's all over, to capture the contrast!). Try different shooting angles, too – standing on a chair to look down at the guests raising their glasses is a classic, or angle the camera to create a more dynamic effect.