If you're not going to pay people, you should probably mention that up-front, and not use the "professional trade" tag.
And as @TwistedTwigleg said, if you're trying to bring people in on your project, use as much detail as possible. People don't want to work for someone that isn't going to fully explain what they need, because they have no idea what to expect to have to do. Artists need details, especially if you want specific art done.
