If you're in search of a fast way of painting units of Orcs then using the products from The Army Painter might be a good way to speed things up a bit. I only have a few hours per month at the most to get some painting done - but I like to play with good looking figures nonetheless. And that's the kind of gamer The Army Painter is making products for. More info on their products on their website:
www.thearmypainter.com.
The image below shows the 3 steps I use to paint my Orc units. As you can see there is quite some contrast in the finished stand with only a minimum of effort.

Step 1: Undercoat + drybrush:
I use the Greenskin coloured primer to undercoat the miniatures. I have the habit of glueing one strip to the stand and the other one on a piece of cardboard, three stands next to each other. After the paint has dried (which only takes a few minutes) I drybrush the stands with goblin green. This immediately provides an additional highlight to the skin and it helps in seeing where the details are for non-skin parts.
Step 2: Base colors:
Then I just apply the base colours as displayed in the picture. Just flat colors, nothing fancy. I also take quite bright colors since the quckwash will darken the miniature quite a lot. Here I used chainmail for the metal parts, bleached bone for clothes, snakebite leather for wood, skull white for teeth and smaller bits and charadon granite for the really dark areas.
Step 3: Quickwash & varnish:
The third step is where the magic happens. With a brush I apply the quickwash (strong tone for O&G) and let the figures dry for at least 24 hrs. After they have dried just spray a layer of matt varnish (I use The Army Painter varnish here is well) over the model and you're done painting.
Just finish the base and the stand is ready for the tabletop.
You can of course use this technique for other units as well, as shown in the pictures below (sorry for the not so sharp photographs).


The chariots and board riders were base coated fur brown, the spider riders and the wolves were base coated bleached bone. The goblins were basecoated black but I painted Charadon Granite on them using an airbrush, only spraying top-down. The skin is only a single layer of goblin green, no other highlighting was used.
I hope this can help somebody on this forum to turn their mountain of lead into a real O&G army without too much fuss.
Cheers,
Jo