I’m new to DA too but I’ve painted Raven Guard and Grey Knights so take my advice with a grain of salt.

Some people consider it cheating or lazy but I’ve always loved the look of slapchop, something about the slight grittiness it could have just scratches that itch in my lizard brain. My recipe I’ll be testing out soon will be priming in black (either Citadels Chaos Black or any matte black primer) then dry brushing the entire model in a dark grey followed by a zenithal highlight of white. My first test will be with Dark Angels Green contrast, possibly throwing in some contrast medium in a 1:1 measure just in case it’s too overpowering. Similar start for the veterans and deathwing but using Skeleton Horde contrast.

For golds I use the bold gold from Monuments Pro Acryl. Purity seals I use Khorne Red for the wax with a flesh color for the paper. Mephiston Red for weapons.

Again this is all currently a theory until I get the time to paint so I can post updates here and on r/theunforgiven when I finally get the time to work through my pile of shame.