
We don't actually strap rockets to her...there's no need to.




This last one is from Fuschia's 18th Century Dress Project (blog), comparing Miss Jay Alexander (from America's Next Top Model) to Adolf Ludvig Badin, a servant of the Swedish Queen Lovisa Ulrika, from the 18th c.

Next, see to your brushes. I am using Photoshop for this painting, but would like it to have the nice "real media" quality you can acheive in Corel Painter. I created a set of 3 brushes to emulate hairy-oily brushes, with one of the brushes only having a few "hairs" in it. I will use the thickest brush for the majority of the painting, and the thinner hair brushes to add texture and particularly to paint in the mane and tail. Too see a tutorial on how to make custom "oily" brushes, click HERE.
Continue establishing your darks with a rich brown, but still leave some of the original yellow and reddish brown showing through. If you need help seeing the darkest shapes on your reference photo, squint at it or blur your eyes. At this point, don't worry about rendering, just the blocky shapes of the shadows and lights. You might be thinking this looks like a mess now, but forge ahead!
Now it's time to start working with your blues. Using blues, instead of black, for your darker shadowed areas lends your subject a life and interest. Blue and orange are compliments, and form a lovely balance and richness for the eye when paired, even in their subtlest forms. Start blending the darkest grey-blue into the shadowed areas.
With the lay-in of colors complete, begin rendering by smoothing and blending. Continue to build up colors, and don't worry about brushstrokes, sketch lines, and base colors coming through in some places. Keep the edges of the shadows and lights fuzzy - hard lines will make the horse look plastic or flayed.
You may decide at some point that your body color is too hot or saturate. I desaturated my reds by using the "Hue/Saturation" tool and reducing the reds only. 
For finishing, I used a regular round brush, with opacity and flow on pressure-sensitive, and cleaned up the edges all around the horse, erasing some of the rough linework and stray paint. I liked the look of the sketch showing through the painting in some places, so I left a bit of it. I also rendered the hooves roughly, with clean edges, and painted in the eye.
I hope you enjoyed this step-by-step! Please notes and comments in the comments section, or post links to your horse painting!