Traditionally, eggnog was made a month before Christmas and allowed to age. However, given the salmonella risk associated with consuming raw eggs, the preparation of eggnog has been updated.
Eggnog should be served cold--it should not sit at room temperature.
Replace raw eggs with either a pasteurized egg substitute or with eggs that have been pre-pasteurized. You can pasteurize eggs at home by heating them until they adhere to the surface of a spoon (slowly heat the eggs to 160F, or 71C). In some eggnog recipes, the entire batch is cooked to destroy bacteria.
In preparing eggless nog, French vanilla pudding makes a good egg substitute. If you'd like to make dairy-free eggnog, replace the milk with fresh or canned coconut milk.