Well, first we should get an idea first. Then I can make a mesh, and UVW it, then you can make the texture, then I can animate it etc. Sound good?
And as far as concept art is concerned, sure! Concept are would be great unless there is already something useful on the net. But, before that ofc, we need to get a general idea.
I guess the best place to start is by figuring out what your best at. What kind of textures are you the best at making?