Well, whenever you have an idea, or feal like you need to draw something for some reason or another, do that, otherwise, when you don't have anything else you want to draw, practice w/ basic shapes and any sort of poses you may have dificulty with, etc.
(I do agree with what said, basic shapes are used to draw pretty much anything and I use them all the time, a sphere for the head, a sort of rounded rectangle for the torso, a sideways rectangle for the hips, and a sphere connecting them at the abs, etc.)

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I say try and get a good pic of your character.

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I really think you should begin with the fundamental shapes of form (Sphere's, cubes, cylinders). Then try to draw objects that utilize those basic shapes. Like drawing a car after trying a basic cube. Or drawing an apple after drawing a sphere, or drawing mallot after drawing a cylinder.

I know it may seem plain, but this is the very first step to proportional drawings, and it'll ensure you with the basics you need to know in order to draw figures.

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