I thought that first picture gave off some nice blue tones in the dark areas and yellow tones in the light areas to play with with hints of burgundy in his coat. Just remember that they are meant to be "subtle" tones and should be blended with more traditional browns, grays and black. The chestnut mare shows off the musculature and structures of the face so well, which is why I also picked that one. The one of me kissing my horse, well, I just thought it was cute in case you are up for the challenge of drawing people...lol. Can't wait to see what you come up with!