RtL, One of those subjective questions where you'll probably get as many different methods as you get posters. For what it's worth I would do the Artillery using Vallejo Dark Prussian Blue (which isn't really that dark) with a touch of Rotring Artists Acrylic black ink for a base coat (you really only need a touch of it, this ink seems to go for ever), then lighten original mix with DPB and do highlights, then either 1. a very, very, very light drybrush with a pale flesh/unbleached linen type of colour or 2.lighten mix with Miniature Paints Royal blue.
The first way gives a really nice weathered look, whilst the second gives a deeper, richer look (but I'd probably use a couple of highlight coats, lightening the last one further with a touch of white.
I've never really got a decent red finish that I was happy with, but I once did a quite nice battalion of SYW Hanoverian Regt.Garde, where I used a grey undercoat, then painted in all the creases with black, then washed a very dark red and progressively highlighted by using same red and mixing in orange. My memory when I finished the unit was that nice as it was, it wasn't worth the effort required, so I switched to French in light grey. 