Christmas cards are a special way to spread joy and good wishes during the holiday season. When writing a Christmas card, it's important to consider the recipient's personality and interests. A warm and personal message is always appreciated, and it can be as simple as wishing them a happy holiday season. You can also include a line or two about something special that has happened in your life or share a memory from the past year. If you're not sure what to write, you can always opt for a classic "Merry Christmas" or "Happy Holidays" greeting.