I feel that a mixture of Frank Quitely Clark Kent and Cris Reeve's portrayal of him in the Superman films to be the best disguise. When you mix that up you get a clumsy, head sunked between the shoulders, Bowlegged, slightly stuttering, might of been a nerd in highschool, cowardly Clark. I not only see the confident exterior when he puts on the red, blue and yellow tights but sort of a exhale. The chance for him to breath and be himself. To me Superman is truly who he is.
I could be wrong though...tell me what your thoughts are guys and what ya think.
Tools> pencil, photoshop, optical mouse
I like seeing pictures like this as they show quite a thought in character design.