Most Wiccish groups celebrate Yule or some sort of solstice celebration. It’s interesting to note though that the four “lesser sabbats” (the solar events of solstices and equinoxes) and sometimes said to NOT have been celebrated by the original New Forest Covens. Gerald Gardner, being a social sort, liked to mix with OBDO folk (Druid recon) and adopted their holidays into the cycle he’d been taught. This is why there are four “greater” sabbats (occurring at the height of the season) and four “lesser” sabbats (occurring at the transition of the season.)
Information you find useful can also go in your book of shadows, along with your thoughts on the information. My dedicants start their book with the following for each Sabbat: A ritual to be performed solitary, a ritual to be performed in coven, one page of chants/lore/incense/other correspondences appropriate to sabbat, one “craft” or other holiday working, and a “fun fact” page. They must also prepare (and include) a full moon ritual for one and for a group, a new moon ritual (or other working) for one and a group, an all-purpose healing ritual, a devotional ritual for working with a God and Goddess of their choice (patrons) and a ritual for working with a totem. By the time the dedication year is up, they have a good skeleton start to a solid BOS. Then they start getting the Traditional stuff.