Freddy Kruger wrote: Now, I want to know the correct amount of edge highlighting to use to show off the details. Like, should I only highlight the outer edges and the sharpest points, or like the pictures edge highlight all the edges (but much neater!) To bring out all the details due to it being unable to have a wash due to its black base colour?
Highlight all of them, but if you want it to look neater, use multiple layers of edge highlights so you can make the more rounded edges look softer and the harder edges look sharper.
You can also use a wash on black models, my "speed painted" night goblins I just spray black, edge highlight with a medium grey, highlight the sharp edges with a slightly lighter grey and then hit it with a wash. You can also base a very dark grey instead of black, but make it a REALLY dark grey, like whatever
GW's darkest grey is (Eshin I think?) and mix it with black paint maybe 1:1 or 1:2 grey:black, it'll give you something very close to black but not quite, so when you throw a black was over it you'll get a bit of contrast in the shadows. The trick is you want it VERY dark grey so you don't just make it look like the model is faded.
The reason I don't bother doing it with my Night Goblins is simply black comes in many spray cans but super-dark grey doesn't