Personally the best success I had with quickly doing "organic" figs (models where they are primarily flesh, fur, scales, horn, rather than metal or clothing) was to prime black, paint colors in brighter shades than I'd normally use, then do a head to toe dark wash. Then touch up any brighter spots with a little highlight. I did dozens of GW Beastmen like this in a single evening's sitting and they came out really well.
