The more I have learned about Epona, the more my personal practices have shifted from being traditional Wiccan to being inspired and informed by historical traditions, from personal gnosis (i.e., listening to Her and following what feels right), and from my horses. There are not a lot of specifics about how Epona was honored (see Epona.net for an excellent summary of what is and is not known). Her artifacts date from approximately 50 AD to 400 AD and are clustered in three regions, mostly in modern day France and Germany.
To learn about how She might have been honored, I read some of the ancient authors, studied Her artifacts, and read a lot of stuff (bibliography forthcoming). Some of the classical writers provide hints about how She was honored, or at least about what might been considered common knowledge. There are a few references from classical authors that provide hints about what might have been common knowledge about Epona. For example, Apuleius in The Metamorphosis (The Golden Ass) describes an altar to Epona in a barn adorned with fresh roses. Professor Greg Woolf, in Becoming Roman: the Origins of Provincial Civilization in Gaul, points out that the Romans allowed almost any deity to be honored so long as the worship was performed in a Roman manner.[1]
In a Roman manner. That was the key then for what I was looking for. Even though there are sites that talk about reconstructing Gallic religion and religious rites, that didn’t feel right. My daily rites are basic: every morning, I leave an offering of incense, some times food like carrots or apple cookies, and listen to Her. I try to keep flowers on the altar too, usually roses. When choosing what goes on the altar every morning, I listen to what feels right. Sometimes it’s carrots and other mornings it’s an apple. (Old offerings and flowers are then left in the woods behind my place.)
When I do something more involved, I may do rites in Latin or French (closest to a Gaulish language that I can speak). It’s felt wonderful — “closer” is the best word to describe it. Sites like Cultus Deorum and Nova Roma have some excellent rites in both Latin and English that are easily adapted.
Every year my celebration for Eponalia changes. It depends upon what feels right at the time. Some years I go to the barn with the horses: honoring Her by spending time with Her sacred animals. Other years, I’ve spent the day making a sculpture (which is currently on my altar). I’ve made offering cakes like mola salsa from recipes online. (See this Nova Roma page for a list of rites and offerings that can be used — some interesting ideas.) I usually have a nice dinner in the evening.
What will I do this year? It depends upon what feels right. Whatever I do, my mares will be part of it.
[1] Woolf, G. (1998). Becoming Roman: the Origins of Provincial Civilization in Gaul. Cambridge, Cambridge University Press. pp. 1-23.