Painting Challenge #1: Carcharodons Cataphractii Captain

In my endless quest to improve my painting skills I've decided to do some odd miniatures just to push my skills. Recently, I've been painting Nurgle Daemons and Tyranids using a grey flesh method that's heavy on the drybrushing. I tried applying the same method to some Empire Crossbowmen's uniforms and it looked bloody awful! On cloth it looked dirty and sketchy and I clearly needed a layered method for what I was trying to achieve.

I've also recently been reading Robbie McNiven's Carcharodons novel Red Tithe and I need to get the desire to start a Carcharodons army out of my system. So I'm going to paint a Horus Heresy Cataphractii Captain I got for basically nothing on eBay because he came with the Chaplain I actually wanted to turn into a Black Legion Sorcerer.

So is a picture of the model from the GW webstore and a list of the things I want to use this model to teach myself:

One: a flat grey armour. Most of the model will be plain Dawnstone grey. The methods I want to learn here are twofold: first, to get a good finish on the light grey, and second to practice recess shading. Terminator armour has large panels and prominent recesses so this should be a forgiving model to practice on.

Two: the white-grey flesh. Its a mutation of the chapter and might be helpful for future undead armies. The main challenge will be to make it look appreciably different from the armour colour.

Three: highlighting black. I'll be painting the cape black because I like the monochromatic look of the Carcharodons. I also really, really want to return to my Black Templars one day and this cape has very prominent creases that even I should be able to follow.

Four: the exile markings, which are what the chapter call those Maori-inspired etchings on their armour. In the novel they're a sort of battle honour tattooed on flesh and then repeated on the armour. A good way to practice my freehand because it doesn't have to look like anything, I'm not trying to replicate an actual shape again and again like a chapter symbol. I'll use the illustration in their Badab War Index entry as a guide but, ultimately, I can just experiment wildly here. I'm thinking the breastplate and lower leg armour would be good areas for it.