|Stock image via mjranum stock at Deviantart.|
For this demonstration, I did my figure drawing in Photoshop. I apologize because the legs are too large, but I just wanted to get a sketch down to show my process.
I learned how to construct a basic gesture skeleton from Andrew Loomis' Figure Drawing for All It's Worth.
Step 1. Determine Line of Action. For cartoony drawings, this also functions as the spine. With the line of action, you're trying to capture the gesture, and it's best to exaggerate it, since the gesture can get lost as you build the figure. I find that a great way to keep this from happening is to draw some distortion in the bones.
This next part is pretty unique to how I set up figures, and I really just do it to keep me honest. Now that I have the basic of the torso down, I go ahead and rough in a rectangle to strengthen the pose.
Unfortunately, I got ahead of myself and skipped a couple steps. The first thing I do is draw in the neck hole, which isn't straight across the top of the rib cage, but rather, placed in front. Then I draw the shoulder's line of action straight across the top of the rectangle, and draw in the 'bone' of the arm. I really rely on the whole spheres, cones, and cylinders most kids are taught to construct figures with way back in highschool, and I recommend it.
Anyway, I use the same method to construct figures of my own as I use to draw from reference.