media creation takes a lot of effort, time and expertise.
No artist is going to join or help you unless you're already using cubes or primitives to manage your game assets and have a working engine or demo of your games final outlook.
People dont want to waist time with developers who have not yet put the effort in themselves.
Write a game document that describes your game, thats a great place to organize yourself as well.
Be very detailed with every aspect covered, consider it an overview of your games layout.
Once you have that document in place, start to develop the games structure using simple primitives that get replaced later.
Only then will you encourage people to help you with your project, prior to that your a risk that it wont come together and people will be wasting time trying to help a dead end project.