this is beautiful. It looks a bit like scratchboard due to such interesting whites. Did you use gouache and brush, pen nib??
I actually used a standard photoshop brush with a low opacity. I have found you can get a really traditional look in cs and layers allow me to correct any mistakes on the fly unlike messier traditional acrylic whites, which can be time consuming, and I am usually pressed for time freelancing for several different companies at once. Art directors do not seem to care if it is traditional or digital as long as the quality is there.