Minimize surprises. If you made physical changes, give the family a heads up. Dyed hair, body piercing or a new wardrobe can shock them. Another good thing to clue parents about is any change of diet. A Christmas duck can't be your favorite if you're now a vegetarian.
Explain to Mom that you need some down time after exams so that she doesn't schedule every moment of your winter break. Chances are that studying for finals exhausted you, and you'll want to sleep a lot at first anyway.
Take responsibility for yourself. While it's nice to turn laundry over to your mom, it's better to go ahead and do it as you've been doing at school. This shows her that you can take care of yourself. If you've been saving up your laundry for three months, the shame alone should get you motivated.
Ask to use the family car instead of assuming it's at your disposal. While you're used to coming and going as you please, your parents aren't and may try to impose an old curfew. Politely explain that you no longer require a curfew, but that you will be glad to let them know when to expect you. Be considerate and call if you're going to be late.
Throw the family a bone and spend some time talking with them. Tell them what you like about college and how you've changed. If conversations go poorly, concentrate on doing winter break activities like watching holiday specials on the television or going out to see holiday lights, so you don't need to spend a lot of time talking.
Remember your siblings. Things have been different without you around and they may resent that you've come home and upset the order of life as they know it. Or they may cling when it's time for you to leave. If you roll with the changes, it will make it easier for them.