Metta, or Lovingkindness, is a beautiful meditation that might be particularly helpful in anticipating family interactions and holiday stress. It’s a traditional meditation in Buddhism. There are several sources that are very inspiring for it:
The Wise Heart by Jack Kornfield – One of the exercises at the end of a chapter on compassion details the process of lovingkindness.
If this is a practice you want to work with a lot, I’d suggest Sharon Salzberg’s book on it – Lovingkindness: The Revolutionary Art of Happiness.
When I began this practice, I found an audio recording by a mindfulness-based psychotherapist named Lisa Dale Miller as 2 part podcast.