Here's the process I use when painting my Novamarines and any split or quartered color schemes. I've actually painted two test models now, but this tutorial is going to focus on the first one. The difference being the use of white armour vs bone colored armour against the blue in the color scheme.
You can switch from white to bone easily enough. The process is the same as how I paint my Deathwing models. That tutorial for bone armour is here.
You might see this banner a little more in previous posts as I go through and make sure my older work is compatible with the new GW paints. If you don't see it, don't worry... the tutorial will still work. Your results may be slightly different in the end. Of course if you're using other brands and such, you may have additional differences. I tell everyone it's worth doing a test model so you can see how something looks in your hands before jumping in with both feet and painting away.
Where to start with split and quartered schemes
I start with the lighter color of the two. Traditionally, your darker colors are more opaque and cover lighter colors easier. If we start with our lighter color, we'll probably have less trouble trying to cover it up as we add our second, darker color to the model.
That means this guy starts with the white armour. Remember, you can skip the white portion of this and use the bone tutorial if you want bone colored armour. Just pick back up with the start of the blue armour and follow along from there.
Start by priming the model white. Follow that up with some touch-up work as needed to make sure you have a nice, smooth coat of paint on there. That will give you a solid base to work with.
The next step is to shade the white. Hands down, the best way (read: quickest and easiest) is to use Secret Weapon minis Soft Body Black Wash. Apply this to the recessed areas of the white armour and allow to dry. Don't worry if you get any on the armour plates as you can clean it up easily once your shading is dry.
The white is finished off by cutting in the blue armour with black paint. I also hit all the metal areas at this point too. Now you need to start being careful because the white is done at this point and you don't want any stray marks.
Painting the blue on the armour
I'll be using the names of the new GW colors from here on out, but this tutorial is backwards compatible as well. If you've got the old colors, it will work all the same.
The blue starts with a base coat of Kantor Blue. You can leave the black showing in the deepest recesses where it looks good. Once that dries, it's a zenithal layer of The Fang. This covers a good portion of the blue areas are really provides the majority of the color of the armour.You'll end up with the Kantor Blue showing only near the undersides and the recessed areas right next to the black.
The final touch to the blue potion of the armour is a fine line highlight of Fenrisian Grey. You don't need to do all of the edges though, just a couple of upper ones to break up the armour plates. And that completes the basic armour.
The rest of the elements
The rest of the model is done to taste when it comes to things like purity seals, storm bolter casing, metals, etc. I'm going to include the formulas I used on my model here for those who want to replicate it.
The helmet: Basecoat of Mephiston Red. Then a series of 3 shades: Carroburg Crimson, Agrax Earthshade followed by Nuln Oil. Once each one of those dry it's a highlight with Mephiston Red again on the upper helmet plates. A fine line highlight with Ushabti Bone along those upper plates really defines the helmet. The eyes are done with Sotek Green followed by a small highlight in the center of the eye with Lothern Blue. This gives them the glowing look.
The storm bolter: The gun is painted with P3 Cold Steel and washed with Nuln Oil. Actually, all of the metal on this model is done that way. The bolter casing is painted P3 Coal Black and highlighted with Mechanicus Standard Grey.
The stone pieces: They start with a base coat of Stormvermin Fur and get a quick shade of Agrax Earthshade to darken them down. Oh how I miss the old Charadon Granite already. It's two line highlights after that. The first of Mechanicus Standard Grey and then a Brand-X light grey color. You could probably use Administratum Grey for the final highlight.
The terminator crux: This too starts with a base coat of Stormvermin Fur and gets a quick shade of Agrax Earthshade to darken it down. The it's a layer of Baneblade Brown over the majority of the crux followed by a highlight of a Brand-X tan color. Kislev Flesh would probably work here. It's one final edge highlight with Ushabti Bone and a shade of Seraphim Sepia to tie it all together.
The purity seals: These start as a base of Rakarth Flesh and get a shade of Reikland Fleshshade. A highlight of Ushabti Bone finishes the parchment off. The seal itself is Mephiston Red with a shade of Carroburg Crimson. If you're going to add text to the parchment, I'd suggest thinned Stormvermin Fur as black is too high of a contrast.
The one last thing I have not covered is the ribbing between the armour joints at the knees, hips and elbows. It's a base of Mechanicus Standard Grey with a shade of Nuln Oil. Easy as that.
Getting the chapter symbol on there
Since I don't have a decal yet (I will soon), I had to freehand the design onto the shoulder. Like everything else, it's not too hard if you break it down into more manageable shapes.
I use a fine detail brush and some thinned Kantor Blue to do all the work. I start by drawing a circle big enough to fit the shoulderpad. From there, I thicken it slightly and clean it up. I add the outward spikes next starting with the compass points first. Top, left, bottom and right. Get those for on and then you can fill in the smaller ones in between those anchor points.
The skull is painted inside the circle first without any thought to the eyes or nose holes. I'm just going for the shape overall. Once I have the shape I want, I go back in with white and add the eyes and nose. If I get those wrong, I clean up their shape with some Kantor Blue again until I like what I have.
Weathering and Basing
I'm not going to get into the process here as folks can weather and base in the style they prefer. This will get you a model that is all set and ready to go. I will say that taking the time to add some weathering and such will really bring the model to life and tie all of the elements on the model together.
Make sure to check out these posts as they might help:
A comparison of my two Novamarine test models and the new GW paints
The trick to freehand is small, manageable shapes
How to paint white quick and easy