Are you sure you havn't got confused? Dark Angles green is the darkest green available unless i'm mistaken, and snot green is lighter, so what you have just described should be shading...

 

Right, Ill try and make it clearer.

I COMPLETELY COVERED his skin in snot green, and took the same paintbrush, got some dark angels green, and did not cover his whole flesh, just most of it by lightly brushing it over the top (not drybrushing, I know what that is).

Maybe it is shading, I dont know.

So, what is highlighting?

 

I paint my orks Goblin Green. Then I shade them with a wash of Green Ink (or the old Ork Flesh Wash but I'm not sure they still sell it)... Finally I highlight with a drybrush of a mix of Goblin Green and Bleached Bone...

 

OK highlighting is painting a lighter colour onto a base colour at the points where light would catch it an make it appear lighter. Commonly this is done by applying thin lines of a lighter colour to the top edges of stuff or by drybrushing a lighter colour, however more experiance painters use wet blending or layering (feathering) to give a more gradual change in colour. Unfortunaltey this later approach is much more time consuming, case in point my Death wing librarian who I have been working on for 4 weeks now and I still have his banners to complete (thank god it is death wing and not imperial guard)

 

OK, thanks for that. I think I will stick to what I done.

 

Whay you did was inconrrect. You've applied a darker colour, over a lighter colour. That means the light is the dark green, and the shade is the light green.

This will make your model quite strange looking, trust me, I did the same thing once.