How to make paper look wet / orchid leaves

[Sushy]

Hey,
right now I'm trying to fold an orchid. I fold the blossoms designed by Robert Lang (ODS). Since the blossom has only one color (One color paper), I want to make it look more realistic by differing the color. So I thought it might look good, if some parts are darker (like it's wet) and some parts have the normal color. Can anyone give me some advices to do so? I don't want to paint or something like that because I think I will destroy the model with it.
Besides, does anyone know how to make nice orchid leaves? I haven't started designing yet, but I could think of making it somehow. Anyway, if there is a nice diagram out there or someone can give me an advice, I would appreciate it.

King Regards
Sushy