when you are all done, its a good idea to go over the area with a polishing compoound, or anything that "restores" paint finish. what they do is lighly sand off the surface of the paint which removes the layer with the grime/adhesive. it should look brand new after that.
if you were 18 and just got a gvr4 for the first time, you'd prolly have enough time on your hands to do the entire car, and would get the "showroom" effect. (get some clay bars)