Are you planning your Camino at Christmas? Maybe you should take some advice into account if you have taken such an unusual decision.
Christmas is not high season on the Camino owing to the bad weather and to holidays so much private accommodation are likely to be closed althought there is usually some places open, albergues usually close on Christmas Eve , Christmas day, New Year´s Eve and New Year´s day. If you want to check the albergues open at Christmas you can link http://www.aprinca.com/alberguesinvierno/
When walking in winter only in big towns or cities on Camino Francés such as Logroño, Roncesvalles or Santo Domingo de la Calzada and Santiago de Compostela will offer accommodation and you might be the only pilgrim in some albergues. Pilgrims are walking longer distances to find places to stay so it is recommendable to plan your Camino carefully.
Besides, you had better bring a good sleeping bag, warm clothes and waterproof boots (take a waterproof shell and pants in case of rain could be a great idea). Weather forecast is unpredictable althought you probably find snow and rain, and cold temperatures as well.
On the other hand, you should remember that sunset is earlier in winter so wearing some bright or reflective clothing on your road walking should be compulsary.
Once in Santiago de Compostela, the city is decorated with Christmas lights and it hosts a traditional charming market (called Mercado de Nadal) in which you will feel the real Christmas spirit surrounded by twinkle lights fickering against the cold night sky and the smell of freshly fried churros in the air. Santiago seems to be an enchanted place not only with the merriment of the twinkle lights illuminating all the historic narrow streets of the old town, but also with the contrast in quietness and continual bustle of people coming and going by.
In regards to food and drink, you had better know that Christmas is also a great time of year to try a few new culinary taste treat and there are plenty of towns on the Camino to enjoy it.
Remember that tapas are a tradition in Spanish bars and restaurants and you are usually served a tapa when you order a drink. In some bars you are even allowed to choose the tapa you want among a list which the waiter/waitress enumerates in a surprinsingly fast Spanish (even locals ask them to repeat the list twice). However, the star dish on Galician tables for Christmas is seafood. Maybe you are not very familiar with shellfish or seafood but if you are in Galicia you should not miss the chance to try it.
So, I just want to wish you a merry Christmas and have a good Camino!