As with your zeds, thin your paints
You have the basic skills needed for high end painting, and whereas these IG are perfectly fine for gaming - especially gaming with large numbers - I can understand your wish to make individual models in small bands stand out for themselves; I went through the same process shortly after signing up here.
Basically, there are two main roads to go when painting minis:
1. If you want to paint many models in as short time as possible, block out colours and use washes and drybrusning for shading/highlights.
2. If you want really nice minis that photograph well up close and personal (
), use layering/blending (this CAN be combined with washes, but you'll lose some degree of control over the colours that way. Paint the entire area with the darkest colour, then add lighter and lighter layers of the same colour (with yellow or white or bone mixed in - there are different views on this).
This is how
I personally went about it:
I purchased some triads - mainly Foundry, but others are available, too, and some empty paint pots of the same type (Black Hat has them).
I then mixed some intermediary shades (this takes a bit of fiddeling, as it seems, not all paints have the same pigment density). I keep a tedious record of my mixes.
I also mixed various colour series based on GW paints, and I will use any paint range that has colours/shades that I find use for.
And then I started experimenting with the layering.
For layering, as opposed to drybrushing, it is important to thin the paint to get as smooth transitions as possible. The more layers with little difference in shade and only a little of each previous layer showing you use, the smoother the result.
(I have heard some refer to this as 'blending' as oppsed to 'wet blending', but I'm not convinced that it should be called anything else but layering).
The final highlights should be a tone or two lighter than you would normally change from one layer to the next, and only be applied to very small areas.
This takes some practice, but look at some of the finely painted minis all over this side for references where/how to apply lighter layers and highlights for nice results.
Some people don't like using pre-mixed colours, but prefer mixing on-the-fly on small palettes, but I find it time-saving to have my mixes ready out-of-the-bottle (and I don't mind that my British Scarlet looks the same every time).
Layering can be augmented by 'wet blending' - a technique where you use very thinned paints, and a second wet brush to draw out the new layer to be more and more transparent, so that the hue of the previous layer shines through, and you get a seamless transision between the layers.
I don't do that, but results can be absolutely stunning.
I hope this helps. If you experience problems with getting the results you want, try finding minis with similar effects on here, and then ask the poster about his MO.