It's something I've thought about doing for a long time, I've just been unsure about the best format that will ensure me a level of creativity while also not disrespecting the models.
My creative niche is fantasy art. From my perspective there's no need for an artist to depict things exactly as they are seen in real life. That's what cameras are for and there are excellent photographers that really know their craft.
Instead of just directly drawing a portrait of someone, I like things to be a bit more surreal and give my art a unique touch. Making things in the realm of myth and monsters. For example; want to be a purple fairy with kitty ears? Yeah I can do that. Add some horns. Grow a tail. How about some wings? Feeling angelic or more infernal?
I think I'll set up a list of design elements and make it requirement to have to choose at least 3 (although there wouldn't be an upper limit) to be considered for fan art. I don't think I'll ever say if someone is chosen or not. I want to stay out of local political and personal drama as much as possible. I don't ever want to answer why someone was chosen and why someone else wasn't since there's no way I could possibly draw everybody. At the end of the day I just want to make art and as a side effect someone will also get some art out of it.