So, considering my recent post on the whole UPG thing, I figured maybe it would be a good time to actually share some of mine, little things I've discovered that aren't historical in nature. In this case those relating to Hekate, but others will come later in the week...
For offerings I have found Hekate calls for the fat rendered off from cooking beef. I believe the first time this happened I was cooking some ground beef on the night of Hekate's deipnon (a monthly festival dedicated to her, which is from antiquity), and I just had the overwhelming urge to save the fat which I would have otherwise discarded, to add it to my offerings that night. I did, and I have tried to do so whenever I cook beef. Apples are another offering I find she likes, that doesn't seem to have been emphasized historically.
I associate red roses with Hekate, and it seems quite a few people actually do this. Someone once said to me they associate no flowers with Hekate, because she was not a 'flowery' goddess, but that's why I like roses for her. They're beautiful, like she is... but they have thorns, they can draw blood, and they have a reputation as difficult to grow. Yet, those that grow them find the time and effort worth it.
I have also come to associate common sage with her (not white/smudging sage). And for stones, labradorite and lava rock. I find wells to be sacred to her, among other deities - perhaps because they are a liminal space, a link to the underworld. In the Orphic hymn she is called "Hekate of the Roads," and this is something I have come to emphasize in my own practice in many ways.
For symbols I tend to look to her historical ones, but there is also the crescent moon with it's 'horns' pointing downward. I associate this with all chthonic deities, but Hekate especially.
I find she likes frankincense and myrrh, although both would likely have been offered at some point in antiquity. Patchouli is another incense for her, as well as other deep earthy scents, or the scent of heavy night blooming flowers. Thick, sort of sweet, the scent of a hot, humid summer night.
I have come to know her as "queen of the night-singing ones," in other words, those insects and other creatures which call at night. Again, very much the sound of summer.
I suppose my associating her with summer is an odd UPG in itself. Many seem to see her more in the autumn weather, and I do see here there as well, she is present all year, but there is simply something about a summer night that makes me think of her in so many ways. Especially when a storm is brewing in the distance. That charge on the air you don't often get in autumn.
As far as other modern practices go, again, there is the Rite of Her Sacred Fires which I celebrated this year. It's not personal, I didn't create it, and a whole bunch of people participate in it, but it is modern. As, at this point in time, I do still celebrate the wheel of the year, and so I honor Hekate at Samhain. Again, perhaps not that unusual in modern paganism, but it is not an ancient practice, so I'll include it. Samhain reminds me a bit of her monthly deipnon festival, and it is one of the liminal times of year, where everything is moving from life to death. To that end, I also associate her a bit with Beltane, the other half of that time, when things move from death back to life.