Christmas Eve was always special when I was growing up. Over the years, we've scaled down the celebration because fewer in the family gather together.
We always had an extra place set, white table cloth (represented purity of Christ), hay in center surrounding red candles (represented humility and the coming sacrifice), and dined on 12 different dishes (represented the 12 apostles). After dinner, we'd head off to church services. When we got home, my grandmother would light the candles on the tree and we'd open presents. Our traditions were a mixture of Polish/Austrian.
Wiki has an article on the 12-dish Christmas Eve dinner and you can read it here
Christmas Eve dinner in 12 dishes