When thinking of how I would actually gild a lily, I thought that dipping it in gold would make the flower wilt and spoil it. So I thought about how I would make it without destroying the shape.
I thought the best way might be to cover it with gold dust or gold glitter. I selected the lily, used Super Blade Pro, with a gold glitter setting, and then set that layer to lighten over the original image. I added a bit of sparkles of the reflection of the light off the gold.