I am busy with a project. in that I have some nighthaunt chainrasp models coming out of the ground/graves. but I want them to look really muddy and dirty like the ones from Poltergeist. I really have no idea how to do this. I have very little understanding of painting, glazing, washes etc etc imho, just consider me as a noob so to speak. so could someone please explain to me how to do this properly ? like what primer color, which colors to use, which ones as washes, glazes, what techniques to use etc. thanks a ton for thinking along !

here is what I want the undead to look like color wise. :

thank you Nap for all those links, will check and study them out later, thank you !