I am curious to see how other modellers confront this spiny subject.
Before, I didn't bother with any shadowing or highlight, and later I discovered that applying artist's black ink, and then washing it off, achieved a very good result, highlighting all the creases and detail everywhere, very quickly and effortlessly. Maybe not a perfect result, but a very good one and good for wargaming.
Question is that the pot itself, being 50 years old has sort of dried up, and now doesn't work not even half as well as it did before.
I have tried Games Workshop Nuln Oil, Vallejo GameColor black ink, Vallejo Wash, and both don't convince me, when you apply looks good, but when it dries it sort of vanishes away, leaving mostly all the figurine darkened, and not much detail highlighted.
I more or less have avoided inks, painting the whole mini black and then applying the next color on top. But this usually gives a very dark appearance, and sort of blurs the general impression. And doesn't look good on classical subjects, in my opinion generally.
I know that for best results, in theory one should be applying lots of different colour layers and highlights, but this method gave me quick and very good details.
Now I am about to buy another pot of artists ink, but it also has the disadvantage that it wears off with water, at least until it has absolutely dried out, which can be a couple of years, but would love to read some of the other techniques / advice used by the great painters of this forum .