Traditionalist Witchcraft the festivals are festive times of celebration, but they are of less importance than the Full Moons and which ones that are celebrated vary considerably from one Trad to another.
Many Trads are likely to keep only some of the festivals while other Trads may keep festivals associated with their honored gods. As an example: Trads that recognize the Roman pantheon, such as Blue Moon Manor, are very likely to keep Saturnalia in addition to Yule.
Each seeker needs to decide for themselves which festivals to observe. Of course, as time goes by, you will gain insight as to which festivals have special meaning to you.
How to Observe
Full observance of a festival involves honoring that day with activities related to that festival. Dedicate the day as a special day.
Before hand, read about the festival you plan to observe. Note that when you do research, Wiccan rituals do not necessarily reflect the historic qualities of these festivals.
Decide upon appropriate activities. I recommend you buy special treats, special foods and drink.
On the eve of the festival (the night before the day of the festival is always the beginning of a festival), light candles and maybe incense. Enjoy a fine dinner. Families with young children may follow the meal with the children's faborite games.
On the day of the festival, do special things you and your family like to do. If you are alone, take a long walk in a park. Meditate. Visit a museum, art gallery, or see a movie.
I would suggest that if circumstances prevent you from doing much, then light a candle and have a glass of wine.
List of Most Common Festivals:
More information on the Full Moon celebrations and the Festivals including a review of each Festival and customs is in the eBook Course material in The Journey to Trad Witchcraft.