indiegraphics

Nicely said Namakoro!  

Just to chime in, for me it's very much about communication and semantics.  The more the director can communicate desired aspects/characteristics of what is needed, the more I can nail down their vision.  

As for finding the right artist for you - Again communication.  Pick a couple you like and open up a dialogue, "hey, I'm working on this.  Is this the sort of art style you do?  Would you be interested in a project like this?  What would be your approach?  Speaking with various potential artists also gives you a "get-to-know-you" buffer, and you can better evaluate if this is a person you want to work with.

Best of luck with it!