If I were you, I'd take a look at some pictures of Vikings and use that as a jumping off point. I agree with what you've said, some more browns and reds would be nice, as the color scheme on these is pretty subdued (although excellently painted nonetheless). Here's a shot from the new show Vikings
http://www.hollywoodreporter.com/sites/default/files/2013/02/vikings_tv_review_a_l.jpg I have no idea how the show is, but if you take a look at how they're dressed, that might help your creative process. Most of them have browns and earthy tones for clothing (and heavily varied between characters, no real 'uniform') and then their shields are where the real splash of color is. Here's a more historical pic
http://burnpit.legion.org/wp-content/uploads/2010/04/viking_waxe.jpg. Again, the armor and weapon are fairly low-key, getting your dark colors, browns, and silver in there, and the shield as well as the cloak is where the color's at. I'd suggest you make a varied, earthy-toned paint scheme for the majority of the model and really hit that vibrant red in the shields, or a pauldron, or a helmet, cloak, etc. That'd be meds.