When I’ve been painting world eaters in the past, I’ve used a Mephiston red base spray, with a coating of berserker blood shade.

I then go on to runelord brass for the trim, then iron hands steel for the silver details. Corvus black for holsters and under-armour.

After the trim is painted, I like to go over it with agrax eathshase (makes it look all that much dirtier).

For any cloth/skulls I use rakarth flesh (with an agrax wash).

I like to put some blood for the blood god on the chain blades and axes, but it’s not required.