I've recently switched gears from painting my beloved Blood Angels and started working on a Legion that I, and many other fans, have been waiting for for a very long time: The Thousand Sons. There's something tragic about their story, how they were loyal and still were turned upon by the very father he tried to warn about Horus' betrayal.
One thing I love what Forge World did was try to create a distinct visual cue for each Legion. There are already several red-colored legions (Blood Angels, Word Bearers, Thousand Sons, and eventually World Eaters) so rather than doing a flat red that is the trademark Blood Angels scheme, they made each red army different so they're recognizable.
Here's the recipe I used to recreate that candy red armor that Forge World uses for their own Thousand Sons models on their website.