Try mixing Yellow Ochre, Burnt Umber, Yellow Deep and white. The key is to intermix them to get the different tones, one color won’t be enough.

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Respectfully – you have way, way, more colors than you need for painting that horse. Too many colors (especially too much chroma) can make things more difficult rather than easier. You need to see/discern value, hue, and chroma in the reference or scene you are trying to paint. This is the hard part. Also, you’ll probably want to pre-mix color strings in several value steps – that makes life a lot easier than mixing from scratch for every new color you need.

Since your horse is in the warm quadrant of the color wheel/color space, black might be the only blue you need. Yellow Ochre (which you don’t have) might be your best bet for yellow (your Naples Yellow Light I think will be too pale). Burnt Umber will be good as your main brown which can also act somewhat like your red. And of course white. But careful about using too much white to lighten – it makes most colors greyer and bluer – that’s where mud soup comes from. If you’re aiming for realism, I don’t think you’ll need much more than that. Maybe a few touches of slightly higher chroma only if/where necessary.

‘twould appear that the OP, new to WC with a post asking us to do the work for him, has not bothered to re-visit. :envy:

You may want a bit of burnt sienna in there for the reddest tones. I can’t get umber to warm up well without it. But look at several yellow ochers before you buy; the color can vary considerably by brand.

I’m jealous. I never had time for fun when I was in nursing school, long, long ago. Sounds like the old joke of walking uphill to school in the snow, both ways, all year round, doesn’t it?:lol: I’m sure I must have had some personal life but all I remember is looking up from the books to realize my fabulous husband had brought me coffee and a sandwich, and then later realizing I’d let the coffee get cold! (I’m also jealous you have a real art store close by. I drive 75 miles or order it in.)

Congratulations on nursing. There is no better job on earth.

Ah, now that the OP has responded…

In addition to the good advice provided above, keep in mind that simply adding white/black is not always the best way to lighten/darken a color. If you find a mix that seems to be about right, but needs to be lighter/darker by just a bit, then you may need to add some color. The slightly shifted hue will often improve appearance.

Browns, and pastels, are among the most difficult colors to match, because their appearance will vary so much with image and lighting. Fortunately, browns are rarely critical.