Dark art: texturing

I’m really “into” Dark Art lately, but I need to refine my technique a bit (a lot actually)
I’m trying to be any good at this texturing technique… i think i got the very basics down, but i need practise at more advanced texturing like they use in dark art (bruises-cuts-sewed skin and stuff-skin that’s peeling off-decomposing flesh-…) all that fun stuff (especially the peeling thing and adding deeeep cuts)
Does anyone know any good tutorials or techniques?