Identify your pastry artists.
Decide how many pastry artists your kitchen can comfortably handle and who you want to include. Ask each guest to come equipped with a few dozen cookies suitable for decorating.
Take a baking inventory.
Take an inventory of your baking and decorating supplies and decide what you'll provide and what you'll want guests to bring. For example, maybe you'll supply all the frosting and trimmings to adorn the cookies, but each guest will need to bring an apron.
Bake ahead of time.
Bake your own batches of cookies before guests arrive. Make sure you leave time for the cookies to cool before decorating.
Clear the counters.
Clear plenty of work space in the kitchen or dining room so everyone will have room to decorate.
Set out the cookie adornments.
Gather a palette of decorations, such as frosting in various colors, cinnamon hearts, silver-ball candies and colored sugars. Set them out, along with tools such as frosting tubes and sugar spoons.
Let your artistic spirits soar, then sample each other's creations along with mulled wine or cider.