hey, one thought... why dont you select the faces you want for the t-shirt.. then extrude them out far enough so its "t-shirt distance" from the body (you may have to extrude in sections). Now just take the edges of the t-shirt arms.. and pull those verts down the arm a bit more.. to give that (inwards) look. DO this for both arms, the neck and bottom of the shirt. For the neck you may want to scale back in the verts around his neck so that it looks like the collar is touching the neck. But yea, the t-shirt you have right now looks cool . Maybe try this and then add a slight cloth modifier . Ok, Just a idea, and btw.. very nice alien .