Welcome to the forums, Makin! Lord Commissar WarriorFish speaks wisdom, but I'll throw in a few additional thoughts here.
AdMech is a bit of a challenging prospect hobby wise, but not in terms of assembly or conversions. Most of the challenge you'll find is the small details and fiddly, "hidden" parts (such as what will be obscured by the cloaks). In this respect, I highly recommend painting your models from the inside out! By this I mean paint inside the cloak first, as well as the legs/torsos to make getting clean results much easier. Take a look at the WarhammerTV video for painting Skitarii Rangers (https://www.youtube....h?v=vLsteSBHEcM) for more details.
As for the Agripinaa paint scheme, it looks pretty similar to the one I used for my Forgeworld. I'm assuming you'll want to start with Citadel Paints, though if you don't want to use them look for an "equivalent" chart for the GW colours I'll be using. For the outside of the cloak, I'd recommend Dawnstone for the basecoat with a Nuln Oil wash and a drybrush of Dawnstone to brighten the colour back up, followed by an edge highlight with Administratum Grey. You should see these techniques used in the WHTV video, above. The inside should be relatively simple, just basecoat with Doombull Brown, do an Agrax Earthshade wash, layer with Ushabti Bone then finish with a highlight of Screaming Skull to get that nice cream colour.
I for one don't consider any colour choice bad for any army, as long as you commit to painting it and stick with it to the end! In my book, the only wrong colour scheme is one you don't enjoy painting or looking at, but it's not a bad idea at all to model your paint scheme on one from a book. I find that many of my projects end up being a bit of "paint by numbers" on the Games Workshop schemes, though I throw in enough of my own touches to still make it something special anyway. Doing an odd conversion here, some fun basing work there or adding accents to your characters or vehicles are all ways to bring your personality into your army.
In the end, just have fun! Once again, welcome to AdMech and I hope you enjoy our forums!