Although I've never done it before I'd like to try more than one light source to create shadows like was done on TOS. That way the parts of the ship mostly in shadow wouldn't be quite so dark. Another thing I'm resisting is some of the lighting tricks that came later beginning with TMP---that of added lighting effects to engines and nav deflectors and such. For me it just doesn't look right on TOS and pre TOS era designs. I think it starts looking too toy like.
No, any physical details I add now will be quite moderate. Same with the variation in hull tones. After I finish those the next major thing will be signage then choosing the true colours for the nav deflector dome and such.