You should not be afraid of experimenting with different angles and styles. Try photographing your subject off-center of the scene. This creates a unique depth and perspective and makes even a picture of a stationary object, such as a candle, appear more distinctive. You will be taking a lot of pictures, so there is no need to expect all of them to turn out. To avoid future conflicts with relatives, do not post photos without their photo approval.
When are trying to stage a group photo, patience will be your greatest asset. Getting your entire family to stop chatting and to focus on you will probably take some time. And, getting everyone to look at the camera without yawning, blinking, or sneezing is another task. Just be prepared to take multiple shots for even one presentable photo and do not let yourself be disheartened if anyone complains; your whole family will appreciate the final product and be impressed by the result of your hard work.
The most important thing to remember is to shoot first and ask questions later. Take as many photos as you can; this gives you wider range to work with and means that you will have a plethora of beautiful pictures by which to remember the holidays.