Painting a picture is kinda' like climbing a mountain (in my case ... taking an extended vacation every few steps up ;o). There may be thousands of routes to get to the top ... some better than others ... pick one. You can take a fall by putting detail in prematurely and having to erase it and start over (very painful).
When we "paint" with a fiber optic brush onto an electronic canvas, many of these difficulties will disappear due to drag & drop and cut & paste and global-local transformations by way of software. It won't be painful then. Kind of like climbing a mountain where a staircase has been erected ... with handrails.Putting a rider on a horse is fairly difficult. One must integrate the horse-rider combo into a single entity. After painting on it for a long while they will seem to weld themselves together ... they settle in. If they don't ... the whole thing is a failure.
Right now the rider is too stiff (along with other things of lesser import). The reason is that the back must be angled more so as to be perpendicular to the given lines. See it? Parallels & Perpendiculars.