After priming the figures and laying down the base coat of black acrylic (to cover up the raw primer paint, which sometimes has a rougher surface than does acrylic), I tried painting the entire horse before moving on to the rider. I glue horse and rider together in one piece prior to priming them. I know that some people keep the two separate and only glue them together at the end.
I use a lot of dry brushing technique on my horses, which means that it is common to have some of the horse color spill over onto the rider. This means that I have to go back and touch up the rider to eliminate the excess paint. However, if I paint the entire horse first, then I don't have to spend time touching up the rider. I simply move on to painting the rider. The net result is that it seems to make the painting process go faster. Also, it eliminates the "dreads" that I get when I paint the horse last. I don't always like painting horses so this dread sort of goes away, i.e. once the rider is finished, so is the entire figure.
On another front, I have found that I am starting to mix my own colors when I paint. Oh, I'll use the base color right out of the bottle, but now I tend to use the base color plus a lighter color mixed in to provide the highlight color to the figure. This way I am sure to get a highlight that is in the same part of the color wheel as the base color. Sometimes using triad paint groups just doesn't give me the result that I'm looking for.