I still have a lot to improve but, fortunately, I have quite capable friends who actually kinda showed me how it should be done.
(And it is way simpler understanding it, rather than doing it... but il all comes to practice); so said, forgive me if I state the obvious:
The layers colour has to be thinned approximately to a glaze
and you
have to unload the excess paint (possibly using a tissue or a paper towel, but a rag may work ^^); this way the brush keeps the point and you keep control.
Many people I know apply a similar style to the base coat; this makes necessary to give 2-3 coats to achieve a smooth colour (but, being the colour very thinned, the 3 layers will not cover any detail); in the same way, if the "glazing" is too thinned, you just give a second layer (when the previous is dry).
The goal is to see the previous layer (darker colour)while applying the new/lighter one.
Note that it's the same principle (with the appropriate colour range) that creates the
NMM effect
Moreover, by covering less surface with each pass (or couple of passes), you'll achieve a gradient (and a better result if you give "sense" to that gradient)
The blend will be smoother if you'll use a slow transition, for example:
pure Caliban Green
2:1 Caliban Green : Warpstone Glow
1:1 Caliban Green : Warpstone Glow
1:2 Caliban Green : Warpstone Glow
Pure Warpstone Glow
etc
The downside of all this principle is that this way is totally time-consuming.
It has to be said that a complex blending (with tens of layers and hues) is usually reserved to showcase models and not to tabletop ones.
For a faster, tabletop effect you could go with something like
Pure Caliban Green
50% Caliban - Warpstone (leaving recesses)
Pure Warpstone Glow
50% Warpstone - Snot (
iirc)
Pure light colour (I keep forgetting the name, Snot green?) on the very edges
If you like a
'eavy metal-like result, I guess you could skip the second to last layer.
If the gradient is too harsh, you could smoothen it with the appropriate glaze.
Of course, anybody feel free to correct if I skipped something... as I said, it is easy to understand, less easy to divulge or apply it
EDIT:
Btw, I have the impressions that the photos are a bit darkish... try and adjust the white balance and/or the lights, it is simpler to see the right colours rather than to guess (and here on dakka there are plenty of nice photo tutorials

)