Advice on setting up a audio studio?

So I want to set up a room for recording vocals. First of all, what is the best SHAPE of room for preventing echoes and other disturbances. I also know it's best to insulate the walls to help sound-proof them, and to cover the walls in a layer of egg-crate foam to dampen any sound bouncing off. Any suggestions to room shape, along with all tips/pointers are appreciated!