UPDATED WITH BETTER PHOTOS
Here is my work in progress for Horus Lupercal. Between myself and Drake we have decided on this colour scheme for all my black armoured Sons of Horus models. It is simple and effective, based around the fluff that the armour was shiny. I dont tend to use scenic bases on my gaming models. One day I will do a display version of each Primarch. For this Horus I have used sand and a stone. I think it will still look effective (and not like Horus drags around a bloody-great eagle head everywhere he goes lol). Please remember he is not finished and the camera quality isn't the best...
Horus Lupercal - I have given him a red shoulder pad based on Justaerin artwork. I don't think there is a right or wrong here: