Adobe Illustrator CS2
Starting an illustration for myself I don't usually have any plan, just an idea of something I want to draw. This piece turned out to be an exercise in curvilinear perspective.
I drew the robot first. I then added the car, man, and road, then realized I'd better do this in correct perspective if I want it to look right. I eyeballed where I thought the horizon should be drawing lines from the car to see where the vanishing points would hit. One hit well inside the picture, and the other way off to the right outside the frame. Without really thinking about how I'd do the rest of the picture, I fixed the perspective on the car according to these vanishing points. I realized quickly that my poor choice of the left-hand vanishing point location would distort everything to the left of that vanishing point, a big Mechanical Perspective 101 no-no.
Unless I wanted to move the vanishing point off to the left (what I should have done in the first place had I been thinking) and redo the car with the correct perspective (NOT a happy thought), the only other solution was curvilinear perspective, keeping the left vanishing point as the center point, sort of like 1-point perspective, and manipulating the perspective in a circular fish-eye lens fashion, much closer to how the humans see things as they turn their heads from the pivot point of the neck and look around. Not a problem really, but more work than I'd considered putting into this drawing. Turned out to be a decent solution, though, as the rest of the illustration fell into place after that. Nothing amazing, but it worked in a fix.
The colors are mostly brown and bluish-green, basically color compliments, with some yellow and violet added for drama and contrast. :)