My suggestion on the shading of the lighter color issue is this.
Start with an off white that is in the yellow/brown area. Shadow with a
brown and maybe a brown/gray for any deep shadows. Dry brush or paint
(depending on what kind of paint you're using. You can't really dry
brush with oils) with white, tinted slightly with your base color, and
then highlight with straight white.
Oh, does the suit have texture sculpted into it? I'd be surprised
if it didn't. In that case, I'd definitely use enamals or acrylics so
that you can get the most out of dry brushing and a darker base coat,
to bring the texture out.
Otherwise, nice work. I too encourage you to take a break more
often. When I take my break from figures, it's usually cars, these
days. I was an armor modeler for many years though. Did lots of
aircraft in my time as well.