The BaseThe base was coated with Citadel Sand prior to primering the model. Now I've checked recently and the sand that GW puts out on the shelves is absolutely not the kind of sand I have that's in a Citadel-branded tub labeled 'Sand'. It's not even the same kind of sand I got in the same tub a few years later. It's this coarse stuff mixed with fine stuff and you'll probably have to hunt it down at a local store that sells model railroad scenery supplies and mix it yourself. You can use other basing materials if you'd like, but I was aiming for a churned earth look so I used the coarse/fine mix that GW used to put out.
The first step was to coat the base with German Camouflage Black Brown (Vallejo Model Color/VMC) thoroughly, getting into all the recesses. Substitutions for this color include Umbral Umber (Privateer Press Paint/P3) or Dryad Bark (Citadel). Both colors are lighter than the German Camouflage Black Brown, but I was actually using P3 Umbral Umber before I switched to VMC German Camouflage Black Brown.
The second step is to overbrush the base with German Camouflage Medium Brown (VMC). By overbrush I mean that you get the color mostly on the top of the texture and leaving the recesses largely untouched. Bootstrap Leather (P3) works as well. I apologize but I don't know the equivalent Citadel color; I can't find anything similar in my arsenal of paints and I won't suggest something I haven't seen in-person. You're looking for a medium brown; not dark and not too light.
The third step is to drybrush the base texture with Buff (VMC). It can be as light or heavy as you'd like but the point here is to give the texture a bit of depth by making the high points pop out. Menoth White Base (P3) was the color I used before switching and any similar very light tan color will serve our purpose. Flayed One Flesh (Citadel) should serve as a handy substitute if that's what you have.
After the model has been finished but before you spray on the sealer, I like to put some U.S. Bluegrey Pale (VMC) around the lip of the base to make the whole thing pop a bit. The idea here is that with so many warm colors, a gray that falls on the bluish side of the spectrum breaks things up a bit. Ulthuan Grey (Citadel) or Celestra Grey (Citadel) are good substitutes. Of the two I would recommend Celestra Grey because it covers better. I guess you could use Frostbite (P3) mixed with a touch of black, but I'm not sure how that would turn out.
After the sealer has been sprayed on, I like to put on tufts of green static grass on the base. Again, the cooler colors of the green static grass help break up the predominantly warm colors of the model.
The Gold PartsBecause the two new paints that Citadel released to paint the Stormcasts' armor hadn't been released when I started painting the free one that came with a White Dwarf, I had to replicate this without them. This might sound weird, but bear with me.
Base all the parts that are gold with Flat Brown (VMC). Make sure you get good coverage because the point of doing this is to create a solid foundation for the metallics that come afterwards. Metallics tend to have a streaky translucency because of the way the pigment works in them, putting down a brown before gold metallics helps solve the problem. Mournfang Brown (Citadel) is an equivalent, though it is slightly more orange and dries a semi-gloss instead of the matte that Flat Brown does. The P3 equivalent is Bloodstone.
Next step is to base all the gold parts again, this time with Bright Bronze (Vallejo Game Color). This layer forms our shade for the armor, so be as thorough with it as you were with the Flat Brown. Molten Bronze (P3) and Gehenna's Gold (Citadel) are acceptable substitutions, though they are not quite the same shade as Bright Bronze.
Afterwards, you will use Gold (VMC) as your mid-tone color, meaning you leave the Bright Bronze showing in the areas you want to create shadow. Substitute colors are Auric Armour Gold (Citadel) and Solid Gold (P3).
Next you will highlight any areas you wish to catch light with Interference Gold (Golden Artist's Colors). There isn't any substitution for this color because it is meant to catch the light and glint. You could theoretically use a mix of white, gold, and silver, but it won't look the same at all. Make sure you get it in acrylic and rinse your brush thoroughly. You can also skip this step if you wish.
The Blue PartsBase the blue elements with Intense Blue (VMC). Macragge Blue (Citadel) or Cygnar Blue Base (P3) work as well.
Layer on Medium Blue (VMC). Substitutions are Caledor Sky (Citadel) or Cygnar Blue Highlight (P3).
That's it for the blue parts. They're more of a matte sheen, so there isn't really any need for adding depth, but I'd probably just add a darker blue and work up to Intense Blue and Medium Blue if I ever needed to.
The White PartsSee, when originally painting my 'sample' Stormcast Eternal, I thought about painting the mask gold. Then I decided not to because most of the figure is already gold and I needed something to break it up. People I've shown my models to agree that the white masks were a good touch.
First base the area with U.S. Bluegrey Pale (VMC). Be pretty thorough about this since this forms our shadows wherever is applicable, the lightning bolts on the shields being a prime example. You can also use Celestra Grey, Ulthuan Grey, or Frostbite (straight this time since we're aiming for a bluish cast to the shadow)
Your midtone is Factory White (Heavy Gear Blitz Colors). Since the availability on that color is somewhat iffy, you may want to make a 50/50 mix of your base color and a pure white instead. I'm not sure if Reaper produces an equivalent in their Master Series paints or what the equivalent in either of the Vallejo ranges are. There aren't any real equivalents in any of the other paint ranges I have on hand; it is a near white with a bluish tint.
Highlight the white areas with a pure white. This is known by various names: Pure White (Reaper Master Series), Ceramite White (Citadel), White Scar (Citadel), Morrow White (P3). Of the two liquid pure whites that Citadel produces, I would recommend White Scar because it does not cover as well as Ceramite White; we're looking to highlight the area, not cover it in pigment. Avoid Praxeti White (Citadel) since it is meant for drybrushing. Personally I use the Pure White since it comes in a dropper bottle.
The Iron Colored PartsThis is mostly the scale mail loin cloth and the business end of the weapons.
First base them with Oily Steel (VMC). You can also use Leadbelcher (Citadel) or Pig Iron (P3); these will net you a sootier look.
Wash with Armor Wash (Secret Weapon Washes). Nuln Oil (Citadel) and Armor Wash (P3) also work; Nuln Oil will darken things more towards black, however.
Next, layer on Gunmetal (VGC). The substitutes here are Runefang Steel (Citadel) or Radiant Platinum (P3). Overbrush if you're dealing with a heavily textured surface like the scale mail.
The Silver BitsThere aren't a lot of things on a Stormcast that are a bright silver, but the procedure is simple.
Base with Gunmetal (VGC) (Or Citadel Ironbreaker or P3 Radiant Platinum).
Highlight with Silver (VGC) (or Citadel Runefang Steel or P3 Quick Silver).
The Red PartsThis includes weapon hafts, armor straps, and belts. The skirt bit on my guys is blue because I didn't feel like adding more warm colors to the model.
Base the part with Burnt Cadmium Red (VMC). It's hard to get an exact match in other lines, but Skorne Red (P3) and Khorne Red (Citadel) are close.
The midtone for these parts is Gory Red (Reaper Master Series). Khador Red Base (P3) and Wazzdakka Red (Citadel) come pretty close. This is where I stop if it's intended to be a piece of leather, like the aforementioned weapon hafts, belts, and armor straps.
However, Liberator-Primes have a bright red top-knot things, which I highlighted carefully with Republique Red (HGBC). Evil Sunz Scarlet (Citadel) is about the only equivalent I can think of; you could use Khador Red Highlight (P3) if you're aiming for that feathery caught-in-the-sunlight look though.
The ParchmentsThis is an old trick.
First base the thing very clearly in Dirty Bone (RMS). Get this pretty solid if you've primered your model black or gray. You can also use Menoth White Base or Flayed One Flesh.
Next, very carefully wash it with Skin Wash (Vallejo Game Ink), making sure you get the recesses that form the parchment's decoration. I used to use Reikland Fleshwash (Citadel), which has a slightly darker brownish tone, more red than orange.
Afterwards, highlight everything with the base color.
This includes all the parts that aren't armor, leather straps, or anything else. It's only the parts underneath the armor
Base with English Uniform (VMC). Or you could use Balor Brown (Citadel), or Rucksack Tan (P3).
Wash with Armor Wash (SWW). I've already mentioned the equivalencies in Citadel and P3 when I discussed the iron colored parts.
In The End...
Obviously there are elements I have not covered yet, such as the angelic wings some of them have or the Dracoth. That's because I have not gotten around to painting those models yet.