as mentioned above,foundation colors are your best friend.
give your minis a nice dheneb stone basecoat(
gw spray gun or airbrush if possible) and start working from there.
mix the dheneb stone with other nurglish colors and apply them.dont cover all of the dheneb stone because after using the armypainter they will stand out anyhow.
i can also recomend applying it with a brush(dark brown shade works best for your needs).
if you have the spraygun or an airbrush you can spray random parts of your mini with different colors.
So:
1:dheneb stone basecoat
2:random spots with dheneb stone/nurglish color mix
3:metals(swords): just boltgun metal with armypainter.
4:!!matt!! varnish is the best finish
if you want fresh blood on your minis:
after painting and the matt varnish paint a mix of red gore and purple on the spots you want the blood on and apply army painter.
you dont want any matt varnish over this,as it wouldnt look wet anymore.
hope this helps ^_^
edit:
heres a pic of one of my lizards with fresh blood ^^