A good starting point and where I first came across this technique is Dave King's marvellous blog (he makes and now sells some mean little retrolicious evil dwarfs too!)
I will preface my post with a little disclaimer though - I'm not the greatest painter in the world and really only strive to get a good gaming standard with my minis - especially as I still have lots more to do to finish this project! So it does feel a bit strange giving tips out as I'm still learning a lot as I paint each mini.
So here goes...
First of all a grey undercoat -
Watered down black ink wash with a drop of matt medium in -
Skin tones - Vallejo Goblin Green with Matt Medium. I use very roughly a ratio of 2:1 paint to medium. I also loosen the mixture slightly wit a little drop of water. Play around with consistency here - what you're after is for the paint to be translucent enough to let the ink shading shine through whilst not being too watery that you can't control it or you need 4 or 5 coats to get any kind of coverage!
Leather brown for... guess what? A leather hood! Same ratio of paint and matt medium.
Other bits for the base coat filled in too...
Now onto highlighting the flesh - matt medium is very handy here too. I use a slightly more dilute mixture of green, lightened with yellow and a bit more matt medium - I try to let the dark black shadows and the darker green tones shine through in all the recesses.
Same for the leather areas - leather brown lightened with buff -
... and the rest of the mini is highlighted -
Rust up the armour - leather brown and orange fire (50/50) mixed with matt medium and watered down - dab it in the chain mail and other areas that would have rust on them. I also dab a few smaller dots of straight brown ink here and there to accentuate the lighter orange -
Now as he's looking a bit pasty its time for the inks! Again matt medium is great for, wait for it, matting down the inks - we don't want to go for the wet look for his skin! So green ink with a healthy dollop of matt medium (not too much or the ink becomes too dilute to shade effectively).
To get that worn and slightly shiny leather effect I use straight brown ink - slightly watered down so the highlights aren't too lost under the wash. Works well for the red leather scabbard as well -
Sepia ink with matt medium for the wood and fur areas. I also go back and put in the eyes and teeth once the green ink is dry - give the teeth a watered down and matted brown ink dab - orcs don't brush their teeth!
And finally once all that is dry I mix up a very watery and matted down black ink mixture and wash the whole mini. Take care not to let it pool anywhere or obscure the eyes and other recessed bits - I usually dab my brush clean and use it to spread the ink more evenly on the mini after the first wash.
So there you have it - a pretty quick and in my humble opinion effective way of achieving a decent gaming standard paint job!