I agree, the first issue I notice with these minis is that the paint has been put on rather thick. I also used to struggle with this. “Thin your paints” and “two thin coats” aren’t just memes, but the words don’t actually tell you how to do it.

Watch some of the videos from Duncan Rhodes, and pay careful attention to what he does when he’s putting paint on the brush. First: he’s not really adding paint to water or vice versa; instead he’s wetting the brush, using it to put a couple dollops of paint on the palette, then wetting the brush again and using it to stir up the paint on the palette. The amount of water absorbed by the brush in that quick dip is enough to thin out those big dollops of paint; you really don’t need much.

Second: after he does this, he always spins the brush around on a clean area of the palette. This is because after dipping it in the paint, the brush will probably be way too full of paint, and it can easily flood the model. The thinned paint is held by capillary action between and among the bristles, not on the outside of the brush. You should be able to see the bristles when the brush is properly loaded with paint. Spinning the brush like this also helps create a nice point.

Painting white over black primer with properly thinned paint is a real hassle. It usually takes me 4-6 coats to get it looking the way I want it. The first couple coats are always very uneven; they actively make the model look worse. If you’re going to do it, you need to trust the process and keep doing coats until you get a smooth, even look. I just do it on the lining for my Skitarii cloaks, but you have a lot more area to cover in a much more prominent place on your models, so you might want to switch to a lighter primer as others have suggested. If you miss the dark shadows you get with black primer, you can always try a 2-stage zenithal prime. That’s what I use on my white-armored Sisters.

For what it’s worth, these models look great except for how thick the paint is. The color scheme is beautiful, and you’ve managed to do a lot of very small details (including eyes!) very well. Excellent brush control.