TRSE: How To Draw Tutorials:
Drawing Front View of a 'Chibi' Character.
Step 2

    Since we're doing the chibi characters, we'll go with a character that is three heads tall. Use your fingers or a ruler to measure a head and then add two more "heads". This method is to help you CONTROL the height of the character on the paper. If drawing a head that is too big can result in having not enough room for the rest of the body, and if you ran out of space, just shrink the head until you can fit at least three "heads" on the paper. If you really want to draw the chibi-characters with really big heads and very small bodies, you can go with the height of just two "heads".
    You actually can adjust the central horizontal line ("Crotch") to get different results. For example, if you want longer legs, all you do is move the "Crotch" line up and you'll get longer legs while getting shorter torso at the same time. Or you can just add some space between the "Crotch" and "Feet" lines to get longer legs without changing the torso size.
    This method works best with the characters that are standing up (or laying down without bending) and any other poses are bit more complicated but don't worry about them for now for there will be an article on the poses.