I purchased this model from Forge World back in 2007 when I went to Gamesday. Last month I finally decided it had need long enough and that I would put it together and get it painted and ready for the tabletop.
Right now I'm mainly going to concentrate on how I painted the skin of the beast. After priming the entire model black, I went through and did the base colors for everything. The skin looked to be the most difficult to reach so I decided to start there with getting some detail painted. The process was actually very simple, using a base color of Caliban Green from GW, followed by a layer of Straken Green. After that I covered it all with a heavy wash of Athonian Camoshade, which is what you see below.
After that, to bring some additional detail I did some highlighting across the top edge of each scale again with Straken Green. It doesn't provide a huge punt of additional definition but I like the result, seen below.
I think this same method could be used on any lizardman or similar mini to get a fairly realistic scale effect. Hope it works as well for you!