In Traditionalist Witchcraft the festivals are festive times of celebration, but they are of less importance than the Full Moons. Note that celebrations and traditions vary considerably between Trads.
Many Trads are likely to keep only some of the festivals while other Trads may keep festivals associated with their honored gods. Some may keep Saturnalia in addition to Yule. Each seeker needs to decide for him or herself which festivals to observe. Of course, as time goes by, you will gain insight as to which festivals have special meaning to you.
List of the Most Common Festivals:
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 traditions and customs of these festivals. Read non-Wiccan books.
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 favorite 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. Do something appropriate to the festival.
I would suggest that if circumstances prevent you from doing much, then at least you might light a candle and have a glass of wine.