Many thanks, all!
Here's an experiment (following the example of last beastman). I've got a few of these recent GW orks kicking around. I have many more of the metal ones from first-edition 40K (everyone called it that, and no one called it "Rogue Trader", at least as far as I remember) and prefer those. But I want to get the later ones out of the plastic pile, so have been thinking about how to do them quickly. Their signature feature is their teeth, so I wanted to find a really quick way of painting them that would emphasise those. So, black undercoat, drybrushing in burnt umber, flat earth and silver-grey, and then some metal drybrushing for weapons and armour and a wash or two over other sections.
The result's hardly stellar, but it was very quick and it does give me a shadowy, hulking form with big, sharp teeth. So I'll do the other six or seven I have in the same way.