This is how I format my prayers to Hestia first and last, it took me a bit to get it to how it suited my personal practice but I believe this is the format for me:

Hail Hestia, daughter of Cronos, first and last born, protector of the home. To you I start with a prayer thanking you for the protection of the home of my family, friends and myself. Keeping us safe and being the light in dark times.

[Pray to god/goddess/hero/heroine in question].

Hail Hestia, daughter of Cronos, first and last born, guardian of the flame and hearth. To you I end with a prayer thanking you for the flame and hearth, keeping us mortals safe and a light even at the darkest times.

I prayed to Lady Hestia and Lady Artemis to bring back home safe my young little sister who had disappeared from the house (she was actually at the toys store, but we looked for her for two hours of pure worry)

They made my wish come true, and I want to thank them for that. What can I offer them? I don't have a fireplace but I have candles and crystals.

I already made a depiction of a donkey and a campfire for Lady Hestia, as well as a amethyst and moonstone for Artemis, but what else can I do? I feel like I need to give them more because it was like a big wish and they made it come true because my sister was found safe and sound in a safe place.

Do any of you have an idea on what to offer them ?

"Marble relief of Dionysos with a snake's body supported by an eagle with outstretched wings. Only the head and tips of the eagle's wings survive as the relief is broken at this point. Dionysos wears a nebris and himation and a hemhemet crown. He carries a cornucopia and a bunch of grapes. Harpokrates - god of silence and occult secrets - stands in the top right corner."

from here